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Impeccable Custom Engine Repair

 "I love Harley-Davidson, but you got to know the truth!"

 I know you love Twin-Cam engine Harley-Davidson motorcycles (I do too) and I know you want to buy one just because it is the cool thing to do and all your riding buddies ride one.  That's okay, I had the Twin-Cam (TC) bikes and I still own a late model Sportster 1200 Custom, but you still need to know exactly what you are buying so there are no expensive bank-busting nasty surprises.  And before you judge wrongly, at the end of this article, I have written strong reasons in this artcle Why You Should Buy a Harley-Davidson Motorcycle! 

This article is about the Twin-Cam V-Twin engine.  It does not expose defects in the Sportster Evolution (which is a flawless engine) or the V-Rod Revolution engine (which has its own unique problems).  

Also, below, at the end of this article read about Harley-Davidson's Milwaukee Eight Single Cam Engine & How It Solves So Many Defects And Problems!

  Plus, for those uneducated souls who believe this article is full of untruths... you will find every instance mentioned herein within dozens of motorcycle magazines over many years time regarding every known defect in the Harley-Davidson frame and engine. 

  What is new?  I boiled down all the defects into one article.  Yet, still... quite a few idiots still believe all of the reputable magazine editors over the years are liars and that Harley's have no defects.  Imagine that!  Well, I assure you these defects do exist - whether you wish to believe them or not - they will not go away simply because the defects exposed hurt your feelings.  

  "For most of you Harley-Davidson riders this article will be a "awful truth" revelation, but one only need read the many V-Twin motorcycle magazines over a long period of time to verify what you read here is indeed not only shocking, but true." 

  "There are serious defects in the Harley-Davidson Twin-Cam engines."

  What defects?  Plenty of them.  Enough to alarm you.  However, you can fix some of these defects and end up with a nice bike.  Yes, even the new Twin-Cam engine Harley's have serious problems.  Even the expensive CVO (Custom Vehicle Operations) bikes have issues not to be taken lightly.

The Code of Silence!

  Those who know, don't tell.  Those who don't know, don't want to know.  Those who find out the hard way are broke and ashamed to admit their bike is defective.  Worse, they believe it is not a defect and will not break again.  It is a sin to reveal defects in Harley-Davidson motorcycles.  Dealers are silent.  Salespersons are silent.  Parts people are silent.  Mechanics are quiet.  All fear losing their job by management if they dare speak of the "defects" so the roar of their silence is deafening!

Okay, here we go...

1.  The biggest problem is the poor design of the cam chain system.  It still uses "shoes" riding on the cam chains that can still wear out, even with the new hydraulic tensioning system, for that is not a true and lasting fix.  What is the problem?  The soft plastic or nylon shoes rub against the two chains and the shoes wear out.  When they do there will be metal to metal contact and this grinding creates metal shavings that creates a catastrophic engine failure.  So bad the entire engine is destroyed; cams, pistons, crankshaft, engine cases broken.  It is a wickedly serious engine design defect.  Be aware... it can fail at 15,000 miles.  Even the new hydraulic system can fail at 40,000 miles or less and those nasty little shoes need replacing at 40,000 miles due to its inherent weaknesses.

"You may hear a sound like the starter motor is running, but if your pipes are loud you may not get even this warning.  The oil pump passages can clog up without making any noise whatsoever except when the engine starts tearing itself to pieces." 

  What is the fix?  You can purchase a gear set that eliminates the cam chains and shoes.  Harley-Davidson should, in my opinion, make this a standard fix and not an after the fact option.  If you can't afford to install the gear system, then you need to disassemble and inspect the inner and outer shoes every 15,000 miles or risk total engine failure.  The shoe material can also clog the oil pump totally destroying the engine.  There are plenty of motorcycle magazines explaining how to fix this nagging problem. 

  Note: But keep in mind that the crankshaft pinion shaft runout (the shaft will hop up & down motion) can not exceed 3-thousands of an inch otherwise the gears will not work.  Also consider your riding style.  If you like to ride hard the runout (unbalancing/misaligning crankshaft webs) can easily creep beyond .003" and the gears will clash causing catastrophic havoc to the engine.  There really is "no fix" for this Twin-Cam engine defect.  Even the new hydraulic system still has chain tension shoes that will eventually wear out and if you don't catch it in time, the shoes can disintegrate just like the old spring-tension system and cause the cam chain to slap against metal causing total engine failure, usually by clogging the oil pump with metal chips.  And, what makes this runout situation worse?  Harley-Davidson used to keep the crankshaft runout balanced to about 0.003" but in the year 2011 to the current Twin-Cam engines the crankshafts leave the factory to allow as much as 0.012" runout which is so huge you can't even install a gear drive kit.  This means the pinion shaft is wobbling wildly right out of the factory creating damaging vibrations to the valve train bearings, etc. 

"Every Twin-Cam engine has the cam chain follower defect, even the new models.  If it has a cam chain it has a problem!  And every single one of these engines will seize up without warning.  Will it be today, tomorrow or next year?  That is the question you have to ask yourself.  It may be ten years from now depending on the miles on your engine, but rest assured it is going to fail 100% guaranteed and guess who is going to pay for it?"

Note:  Be aware that pre '06 Dyna's and the 1999 to 2006 Twin-Cam Harley-Davidson engines are seriously defective and they will blow up.  How?  As the spring loaded cam chain follower fails is shreds plastic material that fouls the rotary gear oil pump cutting off oil flow to the engine causing sudden catastrophic engine failure and destruction.  Also metal to metal contact produces metal filings to disperse into the oil prior to being filtered by the oil filter.  Be prepared to buy a completely new motor.  Rebuilding the engine may not be feasible. 

New Harley Twin-Cam Engines Will Fail Too!

  And don't think you are out of the woods if you have the new hydraulic cam chain tensioners for model years 2007 to present.  They will fail beyond the factory warranty period.  The problem was not fixed, it was only delayed to, on average, fail above 50,000 miles.  Check the fine print in your extended warranty as this cam chain related failure may not be protected.  Yikes!  You may be required to endure expensive periodic inspections to retain the warranty.  The fact the hydraulic cam chain adjusters still have nylon pads rubbing against chains the pads will still wear out and big-time havoc happens!  

"Believe it or not!  When the engine fails it is not covered under warranty!  Dealers will tell you it is a failed maintenance issue.  In other words, you failed to pay the dealer to tear your engine apart to inspect the condition of the cam chain followers on a routine basis.  This is not fair dealings, but it is what you will get when buying a Harley-Davidson.  It's the price you will pay to play."  

Did you read that right?  Imagine if you bought a new car and they tell you you must have the engine disassembled every 15,000 to keep your warranty!  Nobody does that to customers, but Harley-Davidson?  Not cool, bro.  Not cool at all.  This problematic engine defect in the Twin-Cam engine is terrifying, at least I found it so, there is no way I will buy another T-C engine bike.  And that's just one engine defect... read on!  It gets scarier. 

Note:  Are the 2007 and newer Twin-Cam engines safe?  No!  Do not be fooled.  Hydraulic cam chain followers are now used getting rid of the stiff spring that put too much pressure on the followers rubbing on the cam chain, but this is "no cure" as it only "delays" the problem.  Instead of the engine failing at 15,000 to 30,000 miles it now fails at 50,000 to 75,000 miles.  There is only one cure... get rid of the chain system entirely and switch to gear driven cams.  Do your research now and budget your repair.  Do not wait until the engine fails because if you ride a Twin-Cam Harley the engine is going to blow up!  The old spring-loaded cam chain tensioner system affected the 1999-2006 model Twin-Cam engines.  You can upgrade the cam drive system to the late-style hydraulic tensioners with improved low-friction chains or gear drive with the newer cam plate and higher capacity oil pump.  The higher capacity oil pump was introduced in 2007.   Any competent repair shop can guide you as to what you should do with your specific model year H-D motorcycle.

"You won't get a straight honest answer from Harley dealers regarding this awful engine defect.  I have been lied to by dealers and given a run-around by dealer employees.  It just happened again July 2, 2011 in Carson City, NV Harley-Davidson dealer.  The service writer would not answer my questions, gave me a song and dance and refused to forward my questions and concerns to the mechanic or management and frankly upset me with sarcastic comments.  Problem is a problem exists and Harley-Davidson dealers are actively not giving straight answers to customers.  That is a deceptive business practice and it is against the law under false and misleading advertising and dishonest business practices concealing known facts from the consumer prior to sale!" 

Note: You will not hear any rubbing sounds or receive any indications the cam follower has failed even is you have quiet stock exhaust pipes on the bike.  The engine will fail suddenly and catastrophically and it may even take you down to the pavement as the engine oil coats your rear wheel.  This is a dangerous and expensive engine defect nobody wants to talk about, but it is a real threat to your health, safety and your finances. 

New Development on Cam Follower Problem:  Installing a gear drive system is not the cure and may actually cause severe engine damage in the future if installed.  First, the crankshaft run out (up and down, left and right motion, not thrust of the crankshaft) must be within a tight tolerance.  The problem is the gears are "stacked" one upon another instead of side-by-side so if the crankshaft is out of alignment (and it will get out of alignment just with normal wear the crank and camshaft bearings) the gears will "compress together" and that can break the engine cases, bearings, crankshaft, cams and it devastates the engine to near worthlessness.  So, it there is now cure now for the Harley-Davidson Twin-Cam engine.  This indicates why Harley-Davidson has no cure "real" for this cam chain tensioners shoe problem.


  If your Twin-cam engine grenades and Harley-Davidson never told you in writing how to prevent such a catastrophe and how to fix the problem at Harley-Davidson's cost you can win in small claims or Superior court a refund of the purchase price of your motorcycle.  Consult an attorney.  That's what I would do if my engine exploded due to a known manufacturing defect and nobody told me about it in writing when I bought the new or used motorcycle from an authorized Harley-Davidson dealer.  A dealer can not conceal known defects to sell a defective product upon an unsuspecting consumer, but that is what Harley-Davidson and its dealers are doing.  They are even charging riders money to "inspect" their defective engine profiting upon innocent consumers who have no choice but to pay and obey which is illegal to profit from a corrupt business transaction and a bad contract.  I would sue Harley-Davidson and the dealer in small claims court for a full refund of all such recommended inspection costs and/or make them buy the motorcycle back at the full purchase price, tax, license, registration, insurance, etc.


  There is only one fix for this cam chain follower problem and that is to convert the entire cam drive system to gears.  Don't bother with aftermarket fixes that will convert and update your "spring" tension cam chain follower system to the newer "hydraulic" cam chain system for both of these systems are defective and both will fail because it really does not fix the problem, it only prolongs the problem to fail later down the road and usually out of warranty coverage on new bikes.  The hydraulic nylon hydraulic cam follower will still wear out and the plunger piston will exit the bore and no tension will be on the cams and valve float can swallow the valves breaking pistons, rods, crank and cases and the oil pump can be blocked by debris to totally ruin the engine.  A horrendous expensive mess!  The gear cam drive system may be a tad noisier from gear whine but it is way better than a wrecked engine!  But in all reality there is no true fix other than Harley-Davidson redesigning the cam drive system to get rid of those cam chain shoes and not stacking vertically gears to drive the cams.  The cam gears must be aligned horizontally as the Sportster engine so does intelligently.  The crankshaft pinion shaft can be bent when the bearings wear causing the gears to slam against each other... yikes! 

"A lot of Harley riders are "silent" on these defect issues.  They don't want to know.  They don't want the embarrassment.  They just want to ride and not think about it.   Many Harley riders do not even know they are sitting on a time bomb and their engine is going to tear itself to pieces.  Ignorance is bliss, but they all will pay the price."

2.  Most Touring model Harley's have a high speed wobble that can be dangerous.  The engine is not sufficiently secured to the frame causing weaving, wiggling, wobbles and rear wheel steer.  In some cases riders have lost control and crashed.  There is a fix. makes brackets you can install yourself to stop the high speed wobble.  The original Touring Link fits 1993-2008 models and the newer Touring Link fits 2009-2013.  True-Track also makes a fix for Dyna, Low Rider and Touring models.  Some newer Harley's may already have the fix installed, but not all of them, so consider this before buying. The 2011 model year bikes have had the wobble problem repaired.  If your bike wobbles it can be just a steering head bearing needing adjustment, worn shocks, or worn swingarm bearings, even your tires tread pattern can cause wobbles and tire not properly mounted (unbeaded tire) or a warped brake disk or worn wheel bearings, loose spokes should all be checked first.  Dynaligner by Custom Cycle Engineering has a fix for Dyna riders so they can align the engine to the frame to cure wobbling problems.  Purchase the lower and upper adjustable engine mounts that they make.  Custom Cycle Engineering makes an inexpensive steering damper stabilizer to help cure the wobble problem.

3.  Lifter block failure.  The lifters can seize in the blocks or just plain rattle in the bores when worn out.  It is a random thing.  Some engines never have a problem while others will fail.  The failure can be bad as it can hang up a valve so the piston hits the valve and "wham" the engine is blown.  The Evolution Big-Twin engine also has lifter problems and the lifters and lifter blocks must be replaced each 25,000 miles to be safe because at 30,000 miles stock lifters have been known to fail.  The Evo's lifter's roller needle bearings fall apart and this can take out the cam lobes and the oil pump's gears.   The actual hydraulic lifters are also weak and fail and that is another reason why H-D makes upgraded lifters for the T-C engine especially if you hop up the engine as performance cams "slam" the lifters hard.  But even a tiny spec of dirt in the oil can make a lifter fail.  If you have lifter failure you better learn to change your own oil quickly as dirty oil is being left behind causing engine damage.  Dirty oil is simply abrasive oil that is like injecting sandpaper inside your engine or valve grinding compound.  If lifters fail replace all four of them, not just one.  Upgrade to stronger lifters, don't go back to using factory stock lifters!  

"You won't hear about these serious problems from a dealer or salesperson.  But you do have a right to know."  

4.  The shift drum is operated by a spring loaded awl and if this spring fails, and they do fail, the spring falls into the transmission gears and horrific damage takes place.  The rear wheel can lock up, the transmission cases split apart throwing oil all over your rear wheel causing you to crash.  There is no fix for this problem.  It is a faulty design issue.  It would be advisable to replace the shifter awl spring once every three years or 30,000 miles to be on the safe side.

5.  Belt drive can be an expensive problem.  To replace a worn or perforated belt the entire primary chain case must be taken apart along with the bike's swing arm.  It is expensive to replace a belt or the transmission drive pulley because it is time consuming.  Most riders don't even think about this until the day comes they have to replace the belt and find out it will cost them $1,000 or more.  And, believe it or not, a drive belt should be replaced every 30,000 miles even though it may last much longer, if a belt fails, it can cause you to lose control, lock up the rear wheel or transmission and cause a crash.  And new transmission and rear wheel pulleys also need to be installed too driving the cost sky high.  The bill for pulleys and belt and labor may exceed $2,500.  There is a company Super Max that can put a liner on your existing pulleys to save you money.  Did you know that Harley-Davidson Sportster's do not have this problem?  You can change the drive belt in just 30 minutes!  Read our article on Sportster's.  Have you noticed more and more experienced riders are switching to them?  Unlike earlier models you can convert the newer models fit your ergonomics to gain comfort.

"Every 20,000 miles you need to replace the cam chain tensioners on the 99-06 model years of Twin-Cam engines and this replacement is expensive.  But even the new hydraulic-operated cam chain adjusters still have those cam chain plastic followers and they too can and will fail, only later down the road when the engine is out of warranty coverage, so you will pay for it!"

6.  The crankshafts on Harley's can suddenly go out of balance.  The repair is expensive.  I had a new Twin-Cam engine crankshaft fail at just 6,000 miles.  Many riders are lucky, but there is a weakness in the crankshafts that randomly fail.  The crank flywheels are "pressed" together onto the crankshaft and are not welded (crankpin to flywheel) and the crank pin and flywheels can slip.  This is a very old design and outdated in this modern world.  However, welding the crankpin to the flywheels fixes the problem.  You will notice big-inch motors all have welded crankpins to their flywheels to stop this flywheel slipping out of balance problem.  You know you have a slipped crankshaft when engine vibration gets stronger than normal and does not go away.  It will feel like a motor mount has broken, allowing the engine and frame to shake more, but it will be silent.  If you suspect this problem, always tighten the motor mounts and look for broken or worn rubber grommets in the mounts first.  It could be a minor fix.  If not, the entire engine must be torn down and engine cases split to fix the crankshaft.  The dealer may on install a new H-D crank that is not welded... it is still not a good idea even if it is a covered H-D warrantee repair.  Riders who do have vibration problems?  Dealers enjoy telling them, "All Harley's Vibrate!"  This is true, but up to a limit of course.  Don't expect dealers to be eager to fix your vibrating bike.  Many riders are given the run-around even when the crankshaft has shifted out of balance.

  Another problem is the Twin-Cam engines use a pair of straight roller bearings for the crankshaft instead of the tapered Timken roller bearing which is axial load bearing and much stronger and stable.  The straight bearing works when new, but when the engine wears in the crankshaft can "walk" between the split case halves and applies side loading on the connecting rods, rod bearings and the pistons.  It is a bad design and the fix is to install Timken tapered roller bearings and to lock them into place with a securing plate and screws as the crankshaft bearings on Twin-Cam engines are known for crankshaft main bearings to slip out of the case!  These are horrible problems.   Cycle Source Magazine's July 2013 mentioned this problem.


  In 2003 Harley-Davidson changed the left-side crankcase bearing from two Timken tapered roller bearings to a single straight roller bearing.  The new bearing is okay for stock bikes (and Stage I), but if you hop-up the motor (beyond Stage I) you are risking bearing failure.  If you do hop-up your engine you can revert to the stronger duel-tapered bearings.  Why did H-D install cheaper, weaker bearings in the 2003 and later engines?  Makes no sense other than to create engine failures. has the bearings.  It is expensive in labor costs to replace the crankcase bearings as the entire engine must be dismantled and reassembled.  I consider this an engine defect when a strong bearing is removed by the factory only to fail if the engine is modified.  Many riders install larger pistons and cams in their motors and if this weak crankcase bearing is not upgraded a rude awakening of a totally wrecked motor will be the result.  This is not good.


  Changes are always being made by Harley-Davidson so check with your H-D dealer to see if the bike you want to buy has the Timken straight bearing or the stronger duel tapered bearings.  Do not rely on salespersons to give you accurate answers (many do lie).  You may need to ask a mechanic and two more mechanics to verify.  There is a lot of misinformation being circulated. 

"Don't you believe those salespersons and parts managers when they tell you the defects have been fixed in the new Twin-Cam engines... they have not been fixed, the same failures still occur!"

7.  The chrome may look nice in the showroom, but don't expect it to last.  I had a new Harley rusting its chrome in just one year.  The polished aluminum oxidized too.  I was gravely disappointed with my second brand new Harley-Davidson motorcycle.

"Think twice before you buy a Harley-Davidson motorcycle.  Be aware of what you are getting into."

8.  At just 8,000 miles an internal oil leak will develop in the Twin Cam engine's oil pump gears and/or the O-ring between the engine case and cam plate.  This will allow engine oil to leak down into the crankcase when the engine is stopped and cooling down.  So, you need to be aware that if you have an elevated oil tank you can't check the engine oil level when the engine is cold as it will show a low oil level inducing you to add oil and that can flood the engine with oil and cause hydraulic engine damage and even crack pistons and break connecting rods.  Start the engine, warm it up, then check the oil level.  This allow the oil pump time to scavenge oil from out of the crankcase to give you a proper oil level reading on your dip stick. 

9.  After you buy the Harley-Davidson motorcycle make sure the spark plugs are snug to torque specification is a Harley-Davidson motor.  If the plug works loose it will cause expensive cylinder head repairs.  This procedure is covered in the book How to Change the Oil in Your Twin-Cam Harley-Davidson.  Also, make sure the electrical plug connecting the alternator (near the oil filter) is snug and connections are clean.  A loose or dirty connection here will certainly burn up the alternator and rectifier including the circuit breaker.

10.  The above engine problems include the newer twin cam engines even the 2011 and newer models.  There are even more serious problems with older Harley's prior to model year 2007.  So if you plan to buy a used Harley you had better consult with experienced mechanics to identify the known defects before you buy and are stuck with a financial bombshell.

10-A.  Harley's do not retain their value as much as you are being led to believe.  The worst enemy is high mileage, so don't bother riding your Harley if you want to retain its trade-in or resale value.  What is considered too high?  Try 15,000 miles.  That's low for most bikes, but a Harley with that many miles will suffer with a great loss of depreciation in price.  Why?  Because the Harley engine design is old with many seals and gaskets that will eventually fail and leak oil.  The top end runs hot and the piston rings and valves just burn away requiring an overhaul.  If you own a Harley, get an oil cooler as it will extend engine life, but it will not give you any points or dollars when it is time to sell.  One thing a Harley rider will learn soon enough, buy a Harley and you'll lose your money!  Depreciation affects all vehicles, but when low miles become high miles there is a big problem for the consumer.  Be aware!  There is one solution, buy another brand of motorcycle or buy a Harley-Davidson Sportster (see comments below) Why You Should Buy a Victory Motorcycle and use that bike to do most all of your riding and use your Harley just for special occasions.   Of course, if you can buy a Harley-Davidson Sportster model you can have your cake and eat it too. 

10-B. Twin-Cam engines run hot and the larger 110+ size engines run horrifically hot.  So hot the valve guides can crack and dislodge if they are overheated wrecking the engine.  I recommend to invest in a larger size thermostat controlled aftermarket oil cooler to drop the engine temperature.  You could also purchase aftermarket auxiliary electric cooling fans to blow air through the engine cooling fins.  Overheating an air-cooled engine in stop & go traffic is easy to do and the heat will warp piston rings and/or fry valve guide seals resulting in a ruined top-end engine that must be repaired.  Heat kills all air-cooled engines.  Note:  Sportster 1200 engines have zero overheating problems because they have huge oversized deep engine cooling fins on the heads and cylinders, piston oil jet cooling and advanced cooling-oil circulating the exhaust valve seats.  However, I still recommend installing an oil-cooler on all air-cooled motorcycle engines for added protection.  Don't forget to use full-synthetic oil in your Twin-Cam or Sportster engine or risk overheating the engine oil that causes engine damage.   

"Even hiring a mechanic to inspect a used Harley-Davidson motorcycle is useless due to the engine design defects.  A brand new Harley-Davidson sitting in the showroom has the defects."

11.  If you buy a Harley-Davidson V-Rod motorcycle be prepared to pay a small fortune for service as the valves must be manually adjusted and to do that the engine must be dropped down out of the frame.  This is expensive and it will be a routine expense to be sorry for.  The labor and parts to perform the valve adjustment is just terrible considering the other Harley's with hydraulic lifters that never need to be adjusted period.  You had best be prepared to pay for valve adjustments or learn to do the job yourself. Either way you will find doing this job a royal pain in the wallet and a total waste of your valuable time.  Will this be the future fate of all motorcycles?  If so, learn to perform these valve adjustments yourself.

12.  Another terrible problem all Twin-Cam engines have is the dreaded "crankshaft slip."  A perfectly new bike with low miles can suddenly begin vibrating so badly it makes riding no fun anymore, even if the engine is rubber mounted.  I too had a brand new Harley and the crank slipped.  The crankshaft flywheels are pressed together to the crank pin.  Without notice and without cause the flywheels will slip out of alignment and the vibration is born.  What is sad is that the Harley dealers will tell you it is normal when it is not.  They will not fix the problem.  I have met other riders with the same problem and the same bad results.  My brand new Harley failed at just 3,000 miles.  I traded it in for another new Harley and the crank slipped on that one too!  Those were my last Harley-Davidson's.  Two strikes on two brand new Twin-Cam engine bikes was enough for me.  I switched to Kawasaki Vulcan 2000 with a 125 cubic inch V-twin and later to the Victory 106ci V-twin which is a superior designed and reliable motor, but dealership qualifications to perform warranty work I found, in my case, was not up to industry standards.  That is a big problem if the bike you buy can't be fixed quickly, reliably and professionally.  You will find this problem throughout the "power sports" industry, so beware. 

13.  You will notice modern motorcycle engine design eliminates the inner and outer primary case the Harley-Davidson Twin-Cam engine uses.  It is an old design full of flaws and weaknesses using a sloppy chain to connect the engine to clutch and transmission.  It is a source of problems mostly regarding oil leaks from the outer and inner primary gasket and seals for the crankshaft, transmission countershaft and starter motor.  It is not cheap to fix these oil leaks.  And to makes matters even worse that this entire primary chain case system must completely disassembled to change a drive belt, pulley or chain sprocket.  Ask around for a price to do these jobs and it will open your eyes a bit wider.  Your drive belt will need replacing one day and you will have to pay a dear price due to this outdated, unfriendly engine design.  Of course, if you learn to do it yourself it will only cost you time (a lot of time) and parts.  Most riders do not know how to do it.  For example if you look at the Victory Freedom 106ci V-twin engine none of these problems are evident.  You can change a drive belt and pulleys yourself.  There will be no oil leaks from seals and there is only one simple gasket for the primary system.  No chains for it is totally gear driven primary system and it uses the engine oil, not a special primary case oil.  Yes, this engine too has a cam chain but of a totally different design.  A proven reliable design using long cam chain guides like modern car and motorcycle engines use.  If the cam chain guide wears out it will not self-destruct the engine.  But you have to drop the engine out of the frame to overhaul the rear cylinder whereas a Harley can be performed in the frame.

"Roland Sands makes a see-through Clarity design cam plate timing cover so you can visually inspect at least the outer cam chain shoe.  Get one or risk catastrophic engine damage!  Go to"

14.  Harley-Davidson's generally require an oil change each 2,500 miles (newer models 5,000 miles).  And it requires that three oil compartments be drained and filled each with different types of oil; engine oil, primary case and transmission oil.  I wrote a book showing you how to do it.  How to Change the Oil in Your Twin-Cam Harley-Davidson  You will notice it only takes ten minutes to change the oil on a modern motorcycle like the Victory and it only has to be changed each 5,000 miles.  So, oil changing on a Harley will cost you twice as much as other engine designs.

"Most riders are absolutely totally ignorant of the problems they are soon to face with their rides."

 15.  I like Harley-Davidson motorcycles.  I appreciate the awesome look, the sound and the comfort they give along with every conceivable custom option and aftermarket item you can buy for the bike.  But what stopped me from buying Harley-Davidson again and again is the Twin-Cam engine and other problems mentioned in this article.  And I did not like the low trade-in value they gave me on my Harley's.  They don't hold their value like they used to simply because everybody seems to own a Harley these days.  Since then I have bought four new motorcycles and not one is a Twin-Cam Harley.  They need to fix these numerous defect problems before I buy again.  However, I did buy a new 2012 Sportster 1200 Custom as these bikes have zero defects.  They may wear out, but they don't break down like those Twin-Cam engines.  

16.  Transmission trouble?  Yes, there is a problem with the transmission 5th gear.  As the 88 twin cam engine evolved to the 96 cubic inch a strain developed on the gears.  In the year 2007 the inner bearing race was upgraded due to bearing failure.  In the year 2010 the fifth gear was changed to a reverse-helical gear to neutralize the side load on the bearing.  What does this mean to the average rider?  It means if you hop up the engine on any twin-cam engine you risk a major transmission failure.  So, you need to purchase and install a fifth gear and bearing/shaft update kit if you ride the bike hard (which many riders do).  The race on the shaft can move, which lets the seal leak and the bearing walk/wobble more than it should accelerating wear and fail.  Some riders have found this bearing failure twice in 40,000 miles.  Mostly hard-ridden stock 88 and 96 will fail along with those with souped-up engines (pistons, cams including crankshaft long-stroked engines).  But the new 103 cubic inch twin cam are not immune to transmission failure even though they have the updated kit installed at the factory.  Read item #17 below explains the reasons.

"When installing cam gears tell your mechanic to make sure to get a .005" lash on the S&S brand gear's clearance so there will be no whining or rattling noises."

17.  Overheating:  Harley-Davidson engines run hot.  The 88 cubic inch engine ran hot and at the high limits and the 96 cubic inch engine runs hotter yet which is not good for the engine.  The 110 cubic inch engines run exceedingly hotter and so much so a class-action law suit was filed against Harley-Davidson from riders being burned from the engine heat (mostly from the rear cylinder near the rider's thighs).  Heat burns to the skin is not the only problem as heat is an engine killer and the hotter these big air-cooled V-twins run reliability falls drastically.  Don't expect engine longevity with a 103 or 110 or 113+ cubic inch air-cooled V-twin such as the Harley-Davidson design.  Clean synthetic engine oil and a large external engine oil cooler is a must-have accessory, but it only helps engine cooling and not cure these serious excessive heat problems that self-destructs the engine.

"Yes, Harley-Davidson does make a solution for the weak oil pump and spring-loaded cam chain tensioners problems.  They have a replacement oil pump and a conversion to a hydraulic cam chain follower.  It costs about $500 plus labor to install it.  It helps, but does not solve the problem completely."

18.  The Harley-Davidson engine looks nice with all the chrome, but if you really look good you will notice the engine design is so archaic it is truly a problem to behold for there are way too many moving parts inside the engine and in the primary case to wear out and break down.  The transmission is small in size and that means smaller, weaker shafts, bearings and gears are inside.  Way too many moving parts each over-stressed!  This is why you see so many in shops being repaired and broken down on the side of the road being towed back to the dealers.  The engines also run very hot when stock and even hotter when the engine is "hopped-up" and this old engine design just can't tolerate all of that heat.  Oil coolers will help, but will not shed enough heat to stop engine damage from excessive wear.  Even full synthetic oil won't stop the wear due to hot spots in the engine.  Even replacing a drive belt will cause you grief even if you do it yourself for it will take you hours of labor.  It will be expensive for a shop to replace your drive belt.  And with the cam followers going to bite you and blow up your engine you need to consider replacing those followers often like every 20,000 miles (30,000 miles if you have the newer hydraulic followers).  But they can even fail quicker in some cases.  The 103 cubic inch will evolve into even higher 110 and 113+ cubic inch engines that will create even higher stresses and heat and reliability is going to suffer even more.  The way I see it, I will not buy a new Harley-Davidson Twin-Cam engine due to all these defects. 

"Don't even do a Stage-1 tune up on a Twin-Cam engine of any size.  The extra power and heat generated will absolutely wear down your engine into oblivion."

  A good example is to see what Harley-Davidson should have done by redesigning their Twin-Cam engine is to look at a cut-away view of the Victory and the new Indian motorcycle engine.  They have all the modern materials and racing valve gear, etc.  Less moving parts and much stronger parts to boot.  There are limits to the power output of any engine design and Harley-Davidson is tinkering with the Twin-Cam engine to stroke and bore it out to create an engine that just is overpowered for its design.  What happens?  You have a hot engine that self-destructs even under normal running conditions.  Even water cooling a Twin-Cam engine with restrictive water channels will help, but it will not alleviate the inherent overheating problem in the newer big-inch engines.

  Nobody wants to admit it because there is a lot of money repair shops and dealers and after market firms are making hot-rodding these Twin-Cam engines and people are falling for it and paying the price of engine failures.  Just take a look inside the repair shops and you'll see these repair bays are full of broken down Twin-Cam engines.  Yes, even brand new engines! 

  "Most riders put on an aftermarket air cleaner and exhaust pipes and dyno-tune it not knowing this will damage their engine's longevity because the Twin-Cam engine is inherently unstable, weak in material strength and naturally runs exceedingly hot.  If you don't ride it hard you may get lucky." 

  You deserve to know the truth about the Harley-Davidson motorcycle.  Just because you see a lot of them on the road, especially at motorcycle rallies, most riders are absolutely totally ignorant of the problems they are soon to face with their rides.  I learned the hard way too.  I had a new Harley engine crankshaft go out of balance in just 6,000 miles... a brand new motorcycle!  I have seen others suffer the same fate and dealers tell people, "Harley's vibrate.  It's normal." 

  19.  I have seen with my own eyes nightmare stories of customers in tears at repair shops and dealerships paying dearly for shoddy workmanship.  The mechanic ruins the engine and the customer pays for it.  This is why I wrote the book, How To Change the Oil on Your Twin Cam Harley-Davidson Motorcycle which also covers spark plug and air cleaner service intervals.   This book will give you tips on how to prevent engine damage.  You will save a lot of money and service will be done right because you did the job yourself.

20.  The Twin-Cam engine between the years 1999-206 has a very weak oil pump that actually drops oil pressure near "zero" when idling which accelerates internal engine wear.  You can shim the pressure relief valve to gain more pressure, but this is still not a cure as those chain followers wear (as yours are wearing as you ride your bike) the follower debris slowly blocks or destroys the oil pump and the engine will be horribly ruined without notice catching you by surprise.  One day all is well, the next day be prepared to buy a new remanufactured engine.  Don't you trust the warranty you have will cover this failure as it likely will not and you will be stuck with the bill.  How can this be?  Excuses are many and are you  having these followers inspected each year?  Probably not and that is just one loophole that will be used to deny your warranty claim.  There is a fix for the marginal oil pump, but you have to buy an aftermarket cam-support plate.  On late 96'ci engines it will permit you to fit "real" bearings on the outer camshaft journals, where the factory plate has none, and in the earlier engines it will allow you to install a better, late-model oil pump.  The replacement plate is stronger with no flexing.  But remember, as long as you have cam chains and tiny followers pressing on those chains your engine will eventually fail catastrophically unless you solve this problem or are "very vigilant" with frequent inspections.  Those inspections are expensive and most Harley-Davidson riders are not aware of the problem in the first place to bother asking or performing these visual inspections. 

21.  Harley-Davidson motorcycles are huge lumbering beasts that are unstable to ride and tend to slide sideways and fall down when the brakes are applied, mostly the rear brake.  They have balance  and suspension problems.  You have to fight the motorcycle constantly on mountain roads and even on the freeway.  It wanders and floats and most riders just think this is normal and for a Harley-Davidson and it is.  When you hop on other brands of motorcycles you will see a world of difference in handling.  You no longer have to keep inputting steering corrections and fight with the motorcycle to stay on course.

22.  Breather problems!  The 96 and more so the 103ci (cubic inch) Twin-Cam engines do have a breathing blow-by problem where oil is pumped out of the engine's breather vent and is sent to the intake manifold to be burned.  At high engine revolutions and load this oil pumping become worse.  This has always been a problem with big twin Harley's, but controllable to a degree.  Excess oil will dribble down under the air cleaner element making a mess of the engine.  The newer big CVO 110ci Twin-Cam engine has a much more serious breathing problem to the point that riders are being told to lower the oil level by 1/2 to an entire quart of oil to help stop the oil leaks.  Problem is, less oil means less cooling for the engine!  This problem is serious and not yet resolved entirely, but you can install a Baker larger oil pan to the engine which will allow more oil cooling and get the oil quantity back to normal or higher as it is rated for 5.5 and 4.5 quarts of oil.  If the engine piston rings are worn you will notice an increase of oil blow-by as crankcase pressure increases so the original breathing problem become awful and severe.  You will have to overhaul the top end of the motor or install an aftermarket racing compatible breather (such as an S&S cam cover) that can catch this blow-by oil or both.  V-twin engine blow-by can become a complex fix.  You can buy a book titled:  Motorcycle Blow-By a Shower of Sparks by author Rex Bunn and his other book Motorcycle Crankcase Ventilation.  Search Internet for the books.

23.  Electrical problems!  The Twin-Cam bikes 3-phase 45 and 48 amp alternators burn up or they will burn up other electrical components.   There is a cure.  Replace the entire alternator with a new 50 amp unit manufactured by

24.  Harley's have a high theft rate, but so do other motorcycle brands.  In fact, sport bikes are stolen at a higher rate than Harley-Davidsons, but still you need to be careful as there is a huge market for Harley-Davidson parts and lots of chop-shops are operating to fulfill the need.  This is why you may pay more for theft insurance.

"The Twin-Cam engine is pure bad news." 

25.  To change the oil each 5,000 miles (or less) is a relatively complex process and a mystery to many Harley riders who do not know how to perform oil changes on the Twin-Cam engine.  Reason being there are three different oil compartments on the big-twins that confuses people.  And if you look for the oil drain plug you can be side-tracked when you see other bolts that could be oil drain plugs, but are not.  So, if you do not learn to do the job yourself (read my book described below to learn how to change oil, spark plugs, air and oil cleaner) the routine oil change expense will get expensive for you.  Some dealers charge astronomical rates as high as $450 to perform a scheduled routine service and many will charge you half that amount which is still way too high to pay!

26.  More bad news:  The Twin-Cam "stock" engines are being bored, ported and stroked for more power and this is bad news.  The air-cooled engines can't get rid of the heat and internal engine damage is taking place.  Even larger oil pans and oil coolers won't cure the intense heat problem.  Maybe, the new H-D formula Syn-3 synthetic oil will help, maybe not, but worth a try.  Heat kills air-cooled engines and more power generates more heat.  The rear cylinder is especially susceptible to heat-related failure.  The intake facing side of the piston scuffs against the cylinder wall real bad due to heat boiling away lubricant wearing out the piston and cylinder prematurely.  And if you modify the engine to obtain more power than stock you are going to run into trouble with excessive heat, fast component wear and tear and a screaming bank account crying for more funds to replenish your savings.  The Twin-Cam engine is pure bad news. 

27.  As you know all Twin-Cam engines are susceptible to having the crank shaft slip out of balance that requires the entire crankshaft to be replaced for it is cheaper to replace than to rebalance.  It happened to my new bike at just 6,000 miles.  But the connecting rods can be bent in as little as 8,000 miles and that is "normal" riding not horsing around.  Now you know why H-D sells a much stronger crank, flywheel and rod assembly!  And there is another problem of the crankshaft bearing walking out of the case and the engine tears itself apart.  These are all serious design problems and wicked defects inside Twin-Cam engines.  Most riders just don't know of these problems and those that do nobody wants to talk about them. 

   "There is a Harley-Davidson that is flawless.  It is the Sportster Evolution Engine."

28.  Did you know the Sportster engine is near perfect and has none of these Twin-Cam engine problems? It is true.  The Sportster engine is near bulletproof with superior engineering design and workmanship and should have been duplicated and made larger for the big bikes instead of using the Twin-Cam engine.  Harley-Davidson has the wrong engine in those big V-twin cruisers!  The new Sportster's (2004 and newer) have rubber mounted engines and the frames and wheels are being beefed up with better accessories to make this bike a serious consideration.  It's no longer a "girl's bike" especially the XL Custom 1200 and the new models.  The Custom 1200 has a larger 4.5 gallon gas tank, superb engine reliability, no nagging engine defects whatsoever, good ride quality, economical fuel mileage, so check them out!  With mini-ape handle bars, fat 16" tires and a wide touring seat with stronger front forks these Sportster's are not at tiny as the old models were.  About time!  It is also easier to change the oil as there are only two oil compartments to drain and fill.  If you want a reliable Harley-Davidson you really need to consider the new Sportster models.  You'll save a ton of money with the Sportster from price of purchase, insurance, maintenance and fuel economy.  Take one for a test drive.

29.  Remember the cam chain tensioners problems mentioned above?  Well, the "B" Twin-Cam engine is internally balanced with spinning counterweights and more chains are buried deep inside the engine cases that drive those weights.  The chains have more durable tensioners but they can still wear out and will need to be replaced.  But to do so it requires a complete engine disassembly.  Imagine the cost and the bill you will get for this!  Stay away from "B" motors.  Buy a Twin-Cam engine that is rubber mounted to the motorcycle's frame.  Better yet, buy a Sportster 1200 as they have zero defects, a perfect engine design!  Read this article!


 Now here comes even more bad news...

30.  Primary Chain Adjustments.  Remember when we used to manually adjust the primary chain?  Well, the new models have hydraulic primary chain adjusters which uses oil pressure to keep the chain taught.  Sounds great, except there is one problem.  Never should the primary chain ever run tight as it can cause damage to the transmission and crankshaft bearings.  The hydraulic primary chain adjuster is not an adjuster it is a "tightener" which does not loosen so it is not adjusting, it just keeps ratcheting the chain tighter and tighter.  Time will tell, but I believe you will be seeing bearing, chain and gear teeth failures due to this innovation. If you get on the throttle hard then back it off briskly this will trigger the automatic chain adjuster to adjust tightening the primary chain and this is bad news.  It will cause seal and bearing shaft wear and premature chain and sprocket wear and even outright breakage!  There is a fix, but it will cost you some money.  Baker has a Bully style primary cover with an inspection cover so you can manually adjust their Attitude brand name chain adjuster.  Now you can manually adjust the primary chain like the good old days.  Harley-Davidson is advertising and selling automatic chain adjusters for the older Twin-Cam models.  Don't buy it.  Keep your manually adjusted system just as it is.  One more thing, those automatic primary chain tensioners are failing in another way... they wear out and need to be replaced around 40,000 miles.  A lot of riders do not know about this weak part defect!  The old manually adjusted system was way better for us riders.  The new system makes money for dealers!  And, the more powerful the motor, the worse the primary chain will want to ratchet and tighten each time you turn on and off the throttle.  Yes, this automatic primary chain system is defective and can definitely wear out your main crankshaft bearing and the clutch and transmission shaft bearings.  Not good.  Go back to the manual system as soon as you can.  Harley-Davidson also sells a Screaming Eagle high performance manual primary chain tensioner to revert your Twin-Cam engine back to sanity.

 31.  Shaft Flexing.  Take a good look at the H-D Twin-Cam engine.  Notice how far away the end of the primary cover extends on the left side of the engine.  It is hanging way out there in space and so are the abnormally long crankshaft and transmission shafts and here is the danger as those shafts can not be supported by a bearing so the shafts bend, flex and break not on the shafts, but the bearings and cases and also the transmission gears are twisted.  Yikes!  This is due to a poor engine design.  If you look at the H-D Sportster engine it has none of these problems, the shafts are short and the transmission is reversed so the output drive pulley is on the right side of the engine curing the shaft length problem.  I told you the Sportster engine is a perfect, perfected engine, and it is way advanced over the archaic, defective plagued Twin-Cam engine/transmission/primary design.  The shaft flexing is a serious problem on a stock engine.  If you add power you add more breakage, simple as that.  There is no real cure except to convert to a belt drive primary with a Baker 6-speed transmission that will put the drive belt on the right side like the Sportster engine.  You will need a new rear wheel too.  The fix is not cheap, it will cost you less than $10,000.  The shaft flexing is a problem, so don't ride hard, don't take off fast from stops, don't speed-shift through the gears.  If you want to do these things buy a brand new Sportster for it can handle abuse because the engine is sound, solid and strong due to a superior engine and transmission design.

  When the shafts flex they load up the engine and transmission bearings and that creates a bearing failure load on them and the engine/transmission cases which causes them to stress and crack.  Eventually the small cracks migrate to form larger cracks and the shafts will destroy the bearings and/or the cases with no warning.  Catastrophic engine/transmission failure occurs.  Now, if you have a stock bike under warranty you are covered for the repair bill, but that's if you survive the risk of a crash as cracked cases blow oil on the rear tire.  If that does not happen, you may be out of luck if you are out of town on a long trip.  It can take a month to get the bike fixed depending on the season. 

  You may get luck with just bearing pitting loading failure.  It means each time the shaft flexes it take a tiny pit out of the bearing eventually causing the bearing to fail.  It will make a rattling noise and shifting will be jerky and not as smooth.  If you have loud pipes you may not hear the bearing failing until it totally fails, so you need to rely on feel.  You can place your ear on a screwdriver near the bearing to hear the bearings if you are skilled to know what a bad or good bearing sounds like.  You can't inspect these bearings easily.  You must measure shaft run-out with a dial indicator and it requires primary system removal which the average rider does not do.  However, most riders are totally unaware of this shaft flex problem and ignore it until it becomes a major repair.

"Break a clutch cable and you are tow truck bait and forget about fixing it yourself... most riders can't do the job."

32.  You better hope you never break a clutch cable on your Twin-Cam Harley-Davidson especially when out of town.  You can't replace the cable with ease.  Believe it or not, you need to remove the exhaust pipes, right side floorboard, drain the transmission of oil and remove the transmission trap door just to replace a clutch cable on the engine side.  Then you have to reinstall all these items you removed.  On the other hand, you can easily replace a clutch cable on the Sportster without this grief and you can fix it on the side of the road, but the Twin-Cam models it is absolute hell (heavenly if you own a repair shop) for what should be a simple procedure.  It can easily cost you a couple hundred dollars and we are only talking shop costs, not the cable cost, towing, motel, lost time from work, etc., if your cable breaks when you are out of town.  Even carrying a spare clutch cable will do you no good.  And, clutch cables can fail without notice and without showing any signs of fraying or wear.  Ask your H-D dealer how much they charge to replace a clutch cable.  It may surprise you.  

33.  There is a helical gear in the new transmissions and now that is causing problems.  Why?  Simply because a helical gear creates thrust, a thrusting of the transmission shaft to exit out of the transmission case!  While the transmission shaft won't push out the case, it will terribly stress the bearing in the case and cause bearing failure.  If you start riding from a low rpm in third gear then go to wide open throttle you will see the clutch lever on the handlebar flipping back and forth.  This is the thrust acting on the output shaft to the clutch plate assembly.  No cure.  Just wait until bearing fails or overhaul the transmission occasionally.  I know, not great advice, but defective component design make it hard on all riders/owners.  The six speed transmission also are making noise riders complain about.  It won't hurt anything, just your mood as you ride. 

34.  The "compensator" in the Twin-Cam primary case is a shock absorber fixed to the engine crankshaft to smooth out the erratic power pulses a 45 degree crankshaft produces.  Problem is, they are failing.  Find out if you should upgrade yours to a Screaming Eagle racing compensator or aftermarket sprocket.  Some new H-D models already have the upgrade.  If so, you may want to consider changing the size of your compensator sprocket to a one or two tooth smaller (more acceleration) or larger (lower cruising engine rpm).  The latter saves fuel and reduces engine heat at highway speed.  But keep in mind no matter what model year Twin-Cam engine you have the compensator sprocket is loosening and can fall off the primary chain.  The result is horrible engine destruction, alternator ruined with oil soaking the rear wheel from a broken primary case that can cause a nasty crash.  The compensator will not fail (usually) without making some hammering noise from the left side primary case when starting (or running) the engine.  If you hear a loud clunk, get this fixed right away with an aftermarket repair kit.  Jims makes a compensating sprocket lock kit to solve this problem and saves the alternator from damage.  If the compensator sprocket comes loose it will be devastating to the engine and you could crash as the primary case breaks and oil hits the rear tire.  A new improved compensator assembly has come stock on 2011 and newer touring models.

35.  The starter gear has a tendency to wear out a bit too soon due to a soft metal.  If it fails it will not permit you to start your engine or if partially fails it can wreck your primary chain system.  Chances are the gear will just wear itself smooth over time and begin to slip and make a grinding noise, but it can fail and create thousands of dollars in repair cost as that broken gear thrashes everything inside the primary case.  This sort of failure can break engine and transmission cases, bend crankshaft, etc.  You can buy a stronger starter gear on the aftermarket.  The V-Twin magazines have advertisements for this part.  Van Bergen and Greener, Inc., makes a heavy duty unit:  But, before you go and replace any starter motor components make sure you have the updated compensator in your engine primary chain case.  One poor guy wrote in American Iron Magazine (Issue 316) he had replaced his starter motor three times in 11,000 miles by Harley-Davidson dealer due to the older style compensator installed that causes the starter motor failures.  The dealer should have updated the compensator before replacing the first starter motor.

36.  The air cooled Twin-Cam engine runs hot.  Even the 88 cubic inch engines run hot.  The 96, 103 and 110 run even hotter.  You must buy an oil cooler for these big motors.  Yes, even the 883 and 1200 Sportster's should have oil coolers even though they have huge fins as large as the big Twin-Cam engines to shed heat.  Some newer Harley's with the 103 engine come with an oil cooler, but it looks too small to really be of much use.  Aftermarket oil coolers are much larger and will shed more heat from the engine.  Here's a good one for big engines; Jagg fan-assisted oil cooler.  This is important as engine failure can come on just one hot day or a day stuck in traffic.  The cylinder can get so hot the cylinder walls warp out of round and the piston will scuff the wall and seize or bend your connecting rods and the valve guide seals can bake and crack or melt.  Now you got big trouble!  Now you have a huge repair bill even if you fix it yourself (if you know how) it will cost you a bundle.  Get an oil cooler if you Harley does not have one.  It should be thermostatically controlled as cold oil can also damage your engine from oil starvation (high viscosity oil) allowing internal metal to metal contact.  You can see valve guide seals fail at 10,000 to 20,000 miles.  To fix the valve seals right, the cylinder heads should be removed, but there are methods some mechanics will use to replace the seals without dismantling the head from the cylinder.  Sealed Power makes valve seals for Harley-Davidson so check them out.  Cold or too hot oil can wipe out bearings and seals fast.  Go to a motorcycle rally and guess what you will see?  Yep, few bikes with oil coolers!  Those engines will fail soon, and you can bet on it.

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"Learn to Install New Tires on Your Motorcycle and Fix Flat Tires"  click to learn more.  Even Installing and Balancing Harley-Davidson Tires Too... stop paying, do it yourself... it's easy.  

37.  The swingarm bushings in all models of the Twin-Cam bikes are weak.  Yes, they do work, but they just won't last.  You will notice, when they are failing, handling of the bike begins to suffer from wobbling.  If those bushings outright fail it can throw you right off the bike due to a loss of control crash!  These bushings have no zerk grease fittings to lube and they are of a sleeve nature.  Aftermarket has sealed ball bearing kits to replace these weak factory stock bushings.  Contact:  True-Track and Sta-Bo

38.  Be aware that any engine or transmission failure can result in a lock-up of the rear wheel or create an oil breech from the cases that will flood the rear wheel for instant loss of control and a devastating crash.  You got to pay attention to those Twin-Cam Harley's as those defects can bite you hard.  Falling off a motorcycle or crashing into objects can be devastating to your health and to your wealth.  If you use 100% synthetic oil with a large engine oil cooler you can escape from many engine failures.  While it may not solve or cure problems, it will certainly increase the longevity of your engine and transmission and primary system resisting  component failure.  Example:  We know the cam chain tensioners shoes will wear out, but they will last much longer using cool synthetic oil.  Even if the Synthetic oil increases some engine/transmission noise it is better to live with that than a catastrophic engine failure. 

39.  Again, the Sportster frame, engine and transmission has none of the defects you read about here on the Twin-Cam bikes.  The Sportster is actually a perfected machine for it is a racing engine design.  Older riders are wise and jumping ship from the TC to the Sportster.  These Sportster's are being converted into baggers, choppers, touring models and they ride nice now due to the upgrades in suspension and wheels.  With a minor investment of installing taller handlebars, stretch seat, Progressive rear shocks with extending foot pegs a little bit more for tall riders these cost effective modification can give you the comfort of the larger H-D touring models.  With good pipes you won't miss anything because the 1200 Sportster sounds just as awesome as the Twin Cam's. And for those who want to ride with a passenger just install a two tooth smaller countershaft pulley for that extra pulling power.  If you love to ride Harley-Davidson's and find the TC's an expense try the Sportster.  I did and I have no regrets!  It has been one positive experience upon another.  Even parts and accessories, tires, brakes, everything is cheaper including insurance and registration with great fuel mileage too!   

 40. The metal circlips inside the transmission that holds the gears in place are not strong enough and can fail causing massive transmission damage.  The problem is found on 2006-09 Cruise Drive transmissions, but are being watched on late models as a "concern" to be aware of.  If you want to have a better transmission on any Twin-Cam Harley-Davidson replace it with a Baker Drivetrain unit.  They are built strong and will not fail.  But it will be expensive to make the upgrade.  You can purchase their bearings and gears set and install them in the stock transmission case at a lower cost.

41.  Bad brakes?  Yes, the brakes on most all Twin-Cam engine motorcycles have bad brakes.  What does "bad brakes" mean?  Well, it does not mean the brakes won't stop the bike... it means the brake pads are fine, but the brake rotors are overwhelmed by the sheer weight of the bike.  It means the front wheel brake rotors will warp from heat and that is why you have been likely told by a dealer that you need new brake rotors and brake pads.  Harley's are heavy, heavy, heavy bikes and the rotors are just too thin to handle all that weight.  So, do not be surprised to keep paying for front fork brake jobs.  The rear brakes are okay, they just don't heat up as much as the front brakes as most of a motorcycle's stopping power is up front.  Brakes are not covered  under warranty.  Read our article, Harley-Davidson Advice - Let's Talk Harley's! on how to fix your bike, etc. 

42.  Alternator failure?  Yes, the bonding agent that glue the magnets to the rotor fails and the magnets fall away and grind up the alternator coils and can cause serious damage to the crankshaft and primary case components.  Only engine heat high temperature creates this failure, not how much electricity you use.  Too much electricity will burn the regulator-rectifier and will not destroy the engine like a magnet failure will.  Not every T-C engine will see this failure, but those who ride hard or hop-up their engines and have no external oil cooler will likely see it eventually.  If you see leaking oil and the electrical wires from the primary case being pulled into the primary case a magnet is loose and pulling in the wires and total failure is imminent.  You may likely not even get this warning, but you'll hear a grinding or rubbing noise from the primary chain case.

 43.  Crankshaft Run-Out.  This is not a slipping of the flywheels causing an imbalance, it is the warping motion of the right side crankshaft's pinion shaft.  This thin shaft drives the oil pump and cams and it can bend or elongate causing a wobbling motion.  Think of a spinning bent shaft.  Generally it can bend on its own usually from high engine heat, but most riders intentionally bend the shaft with burn-outs, drag racing, pulling wheelies, hammering the throttle wide-open, riding at high speeds (over 90mph) will cause the shaft to bend.  When it does bend too far it can snap or vibrate terribly affecting the engine to fail.  Shaft run-out is so critical if it is out of specification you can't even install a gear-driven cam setup to cure a cam chain shoe failure unless you replace the entire crankshaft.  The harder you ride your bike and the faster you ride you will see crankshaft run-out.  If you drive normally you won't have a problem, in most cases.  However, it is bad news for anybody that has hopped-up their T-C motor as crank pinion shaft run out is coming and it will be expensive to repair.

44.  Buy a used Harley-Davidson?  Can you imagine the problems you will be facing buying a used H-D motorcycle?  Just read this article and realize none of the issues listed here were corrected.  You would be buying a disaster bike!  You got to buy a H-D brand spanking new and keep it under factory warranty, or else!  If you are a mechanic, no problem.  If you are not, you'll wish you were.  If you really love Harley-Davidson's you should learn to repair them yourself or always ride a new bike.  Or consider buying a new 1200cc Sportster and customize it to fit you... they have no defects!  They are the most perfected H-D engine every developed.  Yes, you can hop those Sportster's up to blow away any T-C engine.  Sportsters can get 125 horsepower when hopped-up.  Yikes!  

45.  Defective Fairing?  Yes, on touring models the two upper fairing support brackets are notoriously known to suddenly crack and it is not an easy fix that takes 3 hours time to repair.  The stock H-D replacement brackets will only keep failing making your dealer repair shop very, very happy to serve you.  A welder could charge you $150 to beef up the brackets.  There is a 30-minute aftermarket fix though offered by Bagger Parts that cost only $40. 

46.  Primary Case Oil Leaks?  Yes, there are engine and transmission seals that can fail and leak oil into the primary chain case, but the chain case itself has gaskets that can fail and leak oil.  It is just another weak design to be aware of.  The primary gasket is easy to replace, but engine and transmission seals are not, so expect a big repair bill if those fail usually from overheating and the seals drying up.  Use Harley-Davidson SYN3 oil in all three compartments as that oil has seal conditioners to prevent seals from drying out, cracking and leaking oil.

47.  Clutch basket on stock Twin-Cam engines are known to fail at the steel insert loosening and shearing off.  You'll hear a rattling noise from the primary chain case before it fails completely.  The cure is to replace the weak stock unit with the Barnett Performance Products Scorpion billet clutch basket.  It is super strong so you won't tear it up even with a Stage 4 engine build. The clutch friction disks are also superior.

48.  Many Twin-Cam engines are having trouble with the foot/heel and toe shift lever cracking or stripping the shift shaft splines.  This occurs even when not using a heel shifter (which are notorious for breaking and damaging the shift drum, transmission shifting forks, etc.)  Your best bet is to not use the heel shifter and resort back to a higher quality toe shift lever.  Baker makes a good one that will not break the shifter lever or strip the transmission shaft spline.  Carry a spare shifter shaft with the tools required to replace it.  A broken shift rod can strand you instantly.

49.  A new engine defect for 2014 model year Twin-Cam engine is a baffle has been placed inside the crankcase to prevent oil pumping/sloshing, but the oil is being flung by the crankshaft with centrifugal force that will starve the scavenging oil pump from returning oil back to the oil reservoir.  This defect is new and not yet verified in the USA, but in France and Europe it is getting attention on non-USA websites.  Engine defects are generally kept hidden from the public by manufacturers and motorcycle magazines until a fix is perfected.  I was informed a aftermarket company has already come up with a repair.  I also assume, at this point which may not be accurate, that the defect only affects the big 113 c.u. Twin-Cam engines.  I will update this article item as the defect becomes proven.  Since Twin-Cam engines have always had crankcase scavenging problems, it makes sense the 113 c.u. engine is going to make it fierce to control the oil collecting in the crankcase.  Just another good reason to buy a Sportster 1200 Custom model and be done with it.  That's what I did.  It makes sense to ride with peace of mind and money saved than to keep on paying to have your Twin Cam engine fixed. 

50.  Oil Pump: Newer Twin-Cam engines also have oil pump problems if ridden hard or the engine has been modified.  The problem is not only the oil pump's pressure side, but the suction evacuation side become overwhelmed and can not remove the oil fast enough from the crankcase.  If oil accumulates in the crankcase a piston can hydraulic the oil and the motor will grenade.  The cure is to replace the oil pump with a higher capacity pump such as a Fueling high performance oil pump.  Specify the year of your Twin-Cam engine and modifications made to the engine and Fueling will tell you which oil pump to install.  If you see excessive oil build-up in the cylinder head breathers it is a sign you should back off the throttle and ride with less aggression or get a new oil pump.

51.  Oil Pressure:  Twin-Cam engines have a devastating defect in the cam plate's oil pressure relief valve. This valve should open at 55 psi and be fully open at 62 psi, but too many engines lose oil pressure due to the valve failing and opening at just 20 psi.  When this happens the engine is starved of oil and is ruined.  To fix this problem you need to tap in a new ball valve into the cam plate body which will create a new valve seat and then retest the oil pressure.  A goofy fix for a goofy problem.  A real cure is to use Axtell Mountain Motor Twin-Cam Oil Bypass Valve.  You can expect higher, more stable oil pressure at all engine rpm's, longer oil life due to reduced oil shear, lower oil and engine temperature, improved valve train control and reduced noise all for less than $100 for the kit.  Zippers also sells the kit.

52.  Harley-Davidson uses inferior roller bearings inside the Twin-Cam engine and these cheap bearings do fail.  You will notice when you buy upgraded engine components new Torrington and Timken branded bearings are included.  Those bearings are much stronger higher-grade and way more reliable than stock Harley-Davidson bearings.  Those weak stock bearings are everywhere to be found inside the Twin-Cam engine, crankcase, primary, cam chest, transmission and swingarm.  To replace and upgrade all of the bearings would cost a small fortune in labor, so it is out of the question for most riders.  Keep this weak bearing problem in mind when buying a Harley-Davidson motorcycle.  Sportster's do not have bearing failure problems, but Twin-Cam engines do.  Using oil additives should be used in the Twin-Cam engine (and all other Harley-Davidson models too) to prolong engine life. 

53.  The Twin-Cam engine cam support plate has a bronze sleeve bushing bearing that can wear out prematurely and will wear out real fast once crankshaft pinion shaft run-out (shaft-hop) reaches its limit.  Believe me, even if you have gear driven cams in the Twin-Cam engine, disaster is still just around the corner as the crankshaft pinion shaft begins its wobbling dance and those gears will clash and they can break ruining the entire engine.  The same is true with chain-driven hydraulic cam chain tensioners... those plastic tensioners are still there and they are still wearing out, so nothing has been fixed except the system will fail later on down the road at around 70,000 miles or so. The cure?  There is no cure.  But you can avoid disaster by inspecting the cam support bearings and cam chain followers and inspect gear-driven cams for wear and tear along with measuring pinion gear run-out.  To ignore these items is flirting with disaster as they are weak point defects in the Twin-Cam engine.  You may not hear any warning noise before the engine grenades.  

54.  If you purchased a Harley-Davidson motorcycle with spoke wheels get rid of them as soon as you can and install cast wheels.  This is for your safety as inner tube tires can and do "blow-out" and cause the motorcycle to crash.  Also, you can't fix a flat tire with a tube tire by the side of the road as you can rope "plug" a tire on cast wheel rims.  The spoke tires run hot and you get less miles from your tires.  If you decide to keep your spoke wheels the maintenance of keeping spokes tight is not the only concern.  The spokes break and if you lose more than three spokes the wheel can come flying apart causing you to crash.  But truing the wheel by tightening spokes also causes the spoke hub to wear and the spokes keep loosening no matter how many times you tighten the spokes, so you now have to rebuild the wheel with a new hub and all new spokes too.  It is my opinion spoke wheels are inherently defective old technology that can take your life or limb.  Harley-Davidson does make a tubeless spoke rim for those who love the look of spokes with the safety of a cast wheel.  

55.  Be aware the Twin-Cam engines with the new primary chain case cover (this case has no chain adjustment port hole like the older models have) has a more severe problem than a primary chain that keeps on tightening the chain.  The bigger problem is with 2006 Dyna and Big-Twin Twin-Cam engines 2007 to present date are experiencing worn out inner primary bearing and transmission main shaft inner race failing prematurely.  The ever-tightening automatic primary chain adjuster is overloading transmission and clutch bearings causing the bearings to fail.  This is another serious defect that needs to be corrected.  You can prevent this expensive disaster by replacing that automatic primary chain adjuster with the old style manual unit and replace the primary chain case outer cover with a model that has a chain inspection port that allows you to manually adjust the primary chain.

56.  People complain of the 110ci engine due to two problems with engine noise.  1. Hydraulic lifters fail.  Under all load conditions you will hear a rapping tapping noise and those will be the lifters making noise if they fail.  You will need to replace them so the valves will not float and get hit (swallowed) by the piston. 2. Under light load if you hear slapping noise it is the pistons rocking in the cylinder.  Nothing wrong, just a noisy engine defect.  When the cylinder was bored from 103ci to 110ci the piston sleeve was not made longer and this causes the slapping noise.  You won't hear the noise when accelerating or under a heavier load going up a steep hill or riding with a passenger.  Get used to the piston slap/rattle noise as Harley-Davidson will not repair the motorcycle as they consider it "normal" engine noise.  If you tear down the engine on a new 110ci engine and mic the piston/bore clearance don't be surprised to discover the piston is loose in the cylinder often at the top end of the permissible specification.   This means the bore is almost already too large and soon to wear out or piston to wear out of spec to the bore.  I consider this to be an engine defect.  Harley-Davidson should have done better by boring out the engine cases to fit larger cylinders to fit longer-skirt pistons.  To not do this procedure is a half-ass way of doing things in my opinion and is wrong from the get go.  No competent engine builder would resort to such short-cuts. So, what is the fix?  If the lifters are making noise replace them with aftermarket S&S, JIMS or Fueling lifters as they are stronger and more reliable.  For the pistons?  You will need to bore the cases, install new cylinders to fit the longer skirted pistons, or just live with the piston slapping noise under light load.  I would just live with the noise until the cylinder bore or piston wears thin then replace the pistons with a longer skirt along with cylinders to fit.  The piston slap noise will be history and piston cylinder wear will be greatly decreased and engine longevity increased.

57.  Upgrading a Twin-Cam 103ci engine to the 110ci.  Harley-Davidson sells a bolt-in kit.  The stock 103 cast iron cylinders are replaced by larger and stronger steel-lined cylinders with a 4.070 spigot with a 4" internal bore that equals to 110 cubic inches of displacement.  It uses the stock 2007-up 4.375 stroke crankshaft/flywheels.  The pistons are forged, which also means when they are cold they will "slap" in the cylinders creating some noise until they warm up.  You can use the stock push rods if you use the Screaming Eagle No. 255 cams as these cams have identical heel diameter on the cams.  You get larger cylinder heads with larger valves, pistons, cylinders, cams and stronger lifters with all the gaskets to do the job.  But read item #56 above as the increased engine noise will be ever present.  

58.  There have been problems of Twin-Cam bikes bogging down, stalling, hesitating with rough engine running due to a worn out fuel line inside the fuel gasoline tank.  It is the high pressure fuel line in the tank rubbing against internal fuel pump items wearing a hole into the fuel line so as to lose fuel pressure to the fuel injectors.  And yes, this is a defect that affects the engine.  If your exhaust pipes are not too loud, you can hear the high pressure "hiss" of the fuel being ejected from the faulty hose.  You must fix this problem the moment it makes itself known or risk having the engine stall out in traffic.  Ask your Harley-Davidson dealer about this problem and if it affects your model/year bike.

59.  The oil pump rotors can fail if the cranks pinion shaft has excessive run out (hopping up and down or side to side).  Nothing you do can prevent this crankshaft or bearing failure from occurring.  It may happen in 6,000 miles or never.  It's a crap shoot because the crankshaft flywheels are not welded into position and they can slip on the crank pin causing the imbalance that will ruin the oil pump directly or cause case bearing failure which will then ruin the oil pump.  It just depends on the crankshaft and its case bearings finicky friendly desire to stay intact.  Many riders have also discovered they can't upgrade to the camshaft gear drive system due to the pinion shaft being out of true with excessive run out.  To do so you will need to replace the crankshaft, but I would make sure if you do the flywheels are welded to the crankpin.  Oil borne debris (dirty oil) can cause the oil pump gearotors to wear out and fail, so keep the oil clean in your engine always!  S&S makes larger, stronger, higher-capacity upgraded oil pumps.   The Twin-Cam crankshaft will eventually shift its webs on the crank pin.  Read Baggers Magazine article, "Make More Power" on page 74 December 2013 if you don't believe it they say... "all Twin Cam motors eventually shift and create excessive run-out on the pinion shaft, which could cause extensive damage to your cam plate and oil pump."

60.  Since 2007 six-speed transmissions in the Twin-Cam bikes have developed an annoying rattle when in neutral and has loud shifting.  Some bikes are loud, some are not.  It is not considered a defect as it will not harm anything.  It is caused by tolerance stacking as some parts of the transmission are assembled a bit looser than other transmissions on the assembly line.  The transmission will then make all sorts of bangs and clanks noises if you let the engine rpm drop too low while in a taller gear.  

61.  2011 and later Body Control Module (BCM) Softails and Dynas when you change to LED lights the BCM thinks there's a problem and tries to shut down the light.  Harley-Davidson has a fix for this defect by recalibrating the BCM.  I always recommend buying Harley-Davidson components so you don't run into these unforeseen difficulties and added expense.  Motorcycles have become so electronically sophisticated it is just good practice to buy accessories designed, tested and authorized for Harley-Davidson motorcycles. 

62.  I consider the heel shifter a engine defect as that heel shifter is responsible for bending shift forks and breaking shift drum cogs, springs and the drum grooves.  The fix is easy, remove it or cut it off.  Use your toe to shift gears so you can't put brute force on the shift components.  This is sound advice. 

63.  If your Twin-Cam engine makes a rattling noise at idle, it is the oil pressure failing to keep the valve lifters pressurized with oil causing another problem of starving the engine for lubricating oil and engine damage.  Axtell has a fix for this defect with its oil bypass kit priced at $85.  The oil pressure problem is serious so get it fixed as right away or you'll be needing a new engine soon enough!   SKU Part # 425-103.

64.  Oil drips from air filter at high speed?  It's a breathing problem on many Twin-Cam Harley engines, but before you tear down the engine do this; Perform a cylinder leak-down test to measure piston ring blow-by leakage rate (service manual has the details).  If there is too much leakage combustion blow-by pressurizes the crankcase causing oil in the sump to be forced out of the engine breather and into the air filter intake area.  The next step can be expensive to fix as you need to measure the run out at the pinion shaft of the crankshaft.  The run out is caused by the crankshaft webs (flywheels) scissoring due to a slippage of the flywheels.  This happens when the flywheels are not welded to the crankpin!  A serious engine defect occurs when webs are not welded to the crankpin (Harley should be welding all their crankshafts, but they don't and the misery spreads to us riders).  What happens is the pinion shaft hops up and down (or left and right or both up and down) it screws up the oil pump so it can not pump or scavenge the crankcase from oil flowing sufficiently starving the engine of oil and/or not removing oil from the crankcase sump.  The cure?  A new crankshaft and a new oil pump!  Harley-Davidson no longer repairs crankshafts, they just replace with a new one.  You can have your existing crankshaft trued, rebalanced and crankpin welded to the flywheels (two welds) by a V-Twin motorcycle crankshaft repair shop.  You can also upgrade with a new breather element sold by Harley-Davidson to help solve some oil pumping problems to the air filter.

65.  Safety Recalls - While all motorcycle manufacturers have safety recalls you need to perform a recall search for the Harley-Davidson motorcycle you own or plan to buy and find out if the recall fix has been performed.  Some of these recalls are very serious and may kill you say if the brakes fail or the engine stalls out in traffic, so take these recalls seriously.  It seems there is a rise of safety recalls lately with the Twin-Cam engine motorcycles.

Note:  Sportster crankshaft flywheels are also not welded to the crankpin, but the engine power pulse delivery is way more refined and nowhere near as violent as the Twin-Cam engine.  That's why Sportsters' do not have or need or require a crankshaft compensator to smooth out power pulses.  You won't have any breathing or crankshaft slippage with a Sportster (unless you pull wheelies all of the time you are asking for trouble and the crank will fail by sheer abuse).  With normal riding (and some abuse) Sportster's just don't break.  It's the best perfected race-proven V-Twin engine on planet Earth!  If you want a wheelie machine you need to weld the crankshaft, install a huge rear pulley at a bear minimum to take the shock load off the engine and transmission.  That's what the smart stunt riders do.  


  It is hard on me to write this article as there are so many problems and defects it defies the imagination that such could be the case with such a popular Harley-Davidson engine, transmission and frame.  Whenever I visit a Harley-Davidson dealership and see all the new Twin-Cam bikes it seems among all the glitter the defects are not there (yet, I know better).  With people buying new bikes and riders riding in and out of the parking lot it all seems so good.  But one only needs to take a walk over to the repair shop section and it all comes raging back like a bad storm.  You'll see a lot of stripped down engines being repaired, too many!  The defects are real.  If you do your research you will know that what I write here is not a fabrication.  Many V-Twin oriented motorcycle magazines also report on these many defects and report the cures.  The worse thing you can do is be ignorant and assume nothing is wrong with your Twin-Cam engine for that will only lead to disaster which most riders will painfully realize, unless you are lucky to own a 2004 and later Sportster 883 or 1200 which have zero engine defects.  However, the 883cc size engine's small size and low power output can be considered a defect in its own right that requires a 1200cc piston size upgrade which is why I always recommend buying the Sportster 1200cc engine. 

  You will often notice that the repair shops at H-D dealerships are now being sealed from public view.  They are actually hiding what is going on back there.  What they don't want you to see is that novice, unskilled people are working on your bike.  Tire changes are not performed by mechanics, yet should be as tire mounting errors and failure can kill quickly.  Oil changes are also being performed by parts people, service writers and other non-mechanics.  But this is not what you are paying for.  You are paying top dollar for service you are not getting.  Then, when you add in the severe engine failures due to defects of design the poor bike owner is being scalped.

  I moved away from owning a H-D due to these problems, but when H-D finally perfected the Sportster 1200 Custom (and other models) I tried one and bought a new one right away and I got that H-D experience back (which we all love) but without the ending defects. 

  Many riders are seeing the light at the end of the tunnel and buying the Sportster 1200.  You save money on the purchase and there are no more engine failure repair bills.  You get that reliability we all desperately desire.

  Now, there are egos out there that just can't allow themselves to be seen on a smaller displacement engine and fear being looked down upon by other Twin-Cam owners.  However, I see them as fools.  If I speak to them about the engine defects in their motor/transmission they are "totally ignorant" of them and are sitting on a time-bomb that will wipe them out financially.  Most don't have the $5,000 it will require for a new engine.  I rather ride my Sportster knowing it will never blow up than sit on the Twin-Cam grenade.  Get smart, go buy a Sportster 1200 or at least go test ride one and see for yourself how cool they really are.  You see more of them on the road now because Harley riders are getting smart and avoiding personal bankruptcy. 

  And if you think just because you got money to pay to fix these engine defects that will not be a cure for that engine will fail and fail and keep on failing ruining your vacations and wasting your time until you too get sick of it.  Many riders jumped ship and bought other brands of bikes to get away from the unreliability issues of H-D bikes, but you can now buy the Sportster 1200 and have it all.

  You need to get it out of your mind that the Sportster 1200 is a girl's bike or a beginner's bike.  It was true years ago, but since 2004 up to 2012 many changes have been made to the Sportster that it is now a serious cruiser and with way more reliable power to spare.  It is a new machine for a new crowd of enlightened riders.  H-D has a big winner here.  Don't be left out, jump on board.

  One way I deal with the inferiority complex of pulling up with a Sportster in a sea of TC's is to realize I won't be paying horrific prices for self-destructive engine and component failures for my bike has zero defects.  I push the starter and ride away knowing this Sportster is doing everything I want it to do, and more.  And one more thing, my Harley does not look like everybody's Twin Cam.  I no longer try to impress anybody.  As long as I am satisfied, I win!

  I push the Sportster for another reason.  Many people are leaving Harley-Davidson due to the TC defects have bitten them financially and they are so disillusioned they go buy a Victory, BMW, Honda, Suzuki, Yamaha, etc.  Those bikes will not satisfy a true Harley rider due to the sound and feel of the bike.  There is a way out and that is the Sportster.  Most riders are totally unaware that the new Sportster is a perfected mechanical design with zero defects.  That is amazing and now you know.  So, give one a test ride and consider making it fit you with some minor alterations.  I admit, the stock bikes do need some ergonomic fitment alterations, so do all other bikes too.    

   "Know what you are buying.  Know the defects.  Then prepare."

Final Comment:  Even with all the defects I still like Harley-Davidson motorcycles.  I like the look and the sound (so do you) but I do not want to buy another Twin-Cam bike until the engine defects are resolved which I do not see ever happening with the Twin-Cam engine for it just too old of a design to be reliable.  I had Harley-Davidson motorcycles and I have good and bad memories with them.  They are getting way too expensive to purchase and the mechanical problems associated with that old Twin-Cam engine design is just too hard on the wallet.  At least if you know what you are buying and you know the defects you can better understand how to manage them.  The average rider has no idea just how bad it is until the bike fails and he gets a monstrous repair bill.  What is sad is the bike is not fixed at all, the defects remain and it will break again, and again and again.

  Sound Advice: Don't buy a used Twin-Cam Harley-Davidson motorcycle unless it has a extended warranty as long as you will own that bike.  The moment the warranty expires trade it in for another bike.  Devise a plan where the bike you own is always under warranty, or else! And don't do anything that can cause the warranty to become void.  Never trust or believe a salesperson, a parts person or a service writer sitting behind the counter.  They are all professional liars working for a boss who tells them to say things they should not be saying.  Verbal communications are not to be trusted.  Read the warranty and obey it.  Harley-Davidson does deny warranties if you hop-up the motor to create more power, so beware.  Try to keep the bike stock as much as possible.  Even a Stage-1 tune up can void your warranty depending on which part fails.

  There used to be a stigma riding a Sportster, but no more.  Not with the new models that are hot, hot, hot machines!  And power to weight ratio just can't be beat.  Buy a Sportster!  People are wising up and even aftermarket is now offering "bagger" accessories for Sportster's.  It's a totally new machine!  The new Sportster rides as nice as the big-twins, has quicker acceleration and better handling and is more fun to ride and cost half as much to buy!  Check them out.  And best of all... you avoid all the expensive engine and component failures. Read our article: Harley-Davidson Sportster 1200 & Why You Should Buy One - James Russell   

$$.  So easy a girl can do it!Blinking ArrowHD book cover 

Service your own Harley!  Click here to read about the book.  It will save you lots of $$


Note:  No motorcycle is perfect.  All have drawbacks of one sort of another.  However, serious mechanical problems will be experienced with the Harley-Davidson.  As long as you are aware of the problems and accept the drawbacks you will be a happy Harley owner knowing that you knew beforehand certain problems can arise.  This article exposes them so you can take appropriate action to fix the problems to prevent disaster.  Knowledge is power!  I still like Harley's, but I do not think I will buy another brand new Harley-Davidson Twin-Cam engine motorcycle due to the numerous defects and problems that just don't seem to get permanently resolved.

  "Take steps now to fix the problems.  Don't ignore them.  They won't go away." 

  None of the above problems are secrets.  You will find these issues mentioned in motorcycle magazines at one time or another.  You certainly will not hear about them from other Harley riders as most are not even aware of these problems.  You won't hear about these problems from a Harley dealer or salesperson.  But you do have a right to know.

"Show me proof what you write is true."

  Some readers of this article ask for validated proof of what I have written is true.  I can gladly say if you subscribe or purchase back issues of V-Twin Magazine and other motorcycle magazines you will have read about these defects.  It is common knowledge in the industry these serious abnormalities exist.  It is no mystery except for the fact most Harley-Davidson riders are totally not aware that these defects exist and they ride in a land of oblivion mindset... until they have to pay the bill.   Road Iron Magazine exposed the cam defects in January 2013 issue as did Baggers Magazine too.  Most magazines have covered the defects which leads me to believe the "code of conduct" among riders is still strong.  Perhaps, if they ignore the problems the problems will go away?  Pipe dream. 


There are reasons why you should buy a new Harley-Davidson motorcycle.  Here's a few reasons why:

1.  Harley's are made in the USA and that is good enough reason alone.

2.  You can have the engine remanufactured (rebuilt) by the factory.  You just ship the engine to Milwaukee, they completely prefabricate the engine back to OEM specifications, dyno test and tune the engine and ship it back to you or they dealer of your choice.  You can't do this with other brands and it is cheaper to do this with Harley-Davidson than it would to pay anybody else to overhaul your engine.  This service is not available for the Sportster engine, reason being there is no call for it, the engines do not fail like the Twin-Cam engines do.

3.  You can buy anything you need or want for a Harley.  Just look at the accessory catalogs and see what you can buy.  No other motorcycle brand has such a huge selection.  This is one good reason to buy a Harley-Davidson motorcycle as hundreds of companies support the bikes making all sorts of goodies.  Example:  you can buy complete handlebar sets with all the electrical wires and cables ready to just bolt on.  Other brands?  You got to cut the wires and void your warranty (or make extensions with matching harness connectors) and you may be surprised to find risers or handle bars that will not work with your bike.  You can buy different size pulleys, wheels, seats, brakes, luggage, racks and the list is really extensive.

4.  The engines (except the V-rod model) require no routine valve lash adjustments.  This saves you hundreds of dollars in servicing expense each and every year.

5.  Harley riders have the most reasons to ride to destinations and meet with each other like no other group of riders.  Each month there are dozens of advertised locations where bikers are riding and meeting for lunch, charities and just fun rides.  Ain't nothing like it!

6.  No matter which Harley-Davidson dealership you visit you are always made welcome and there is hot coffee waiting for you with snacks.  I dread going into other brand dealerships only to be not greeted, no coffee, no snacks, no friendliness at all and being unwelcome and being assaulted with obnoxious loud music where you can't think or talk to anyone in comfort.  I have traveled all over the nation and the Harley dealers are destinations in themselves just to ride to and many riders do just that visiting dealers as a hang-out and to meet other riders.

7.  If you break down in your travels there are many mechanics who can fix your Harley-Davidson in every town you happen to be.  This is not so with other brands of motorcycles where you may have to tow your bike hundreds of miles to get the bike to a dealership or independent shop that can fix your bike.

8.  I have seen and heard and read endless stories of a rider breaking down and the Harley-Davidson dealer bending over backwards to get the rider back on the road in just hours, even keeping the entire shop open so a mechanic can work on the bike after hours and giving the rider a discount on top of it all to ease the pain of the breakdown.  You won't get that royal treatment with other brands of motorcycle dealers, no way!  They will not treat you well and that I know from personal experience. 

9.  The Harley Owner's Group (HOG) also has thousands of rides, events and meets nationwide.  No other manufacturer has so many loyal members.

10.  The Harley-Davidson Sportster is a good bike for one rider at 1200cc engine.  The engine is reliable and quite bulletproof in design.  Just add an oil cooler (all air-cooled bikes should have one), a touring seat, pull-back handlebars, extended controls, saddlebags, rack and sissy bar and other options if you wish and away you go.  Get a model with cast wheels so flat tires will not leave you stranded, or option to install tubeless spoke rims.

11.  There ain't nothing like the Harley-Davidson experience for pure cruising!  The bikes have a "soul" and that's something the other brands just don't have.  When you ride one, you'll feel the difference!

12.  The 45 degree V-twin engine is the improper firing angle for an ideal engine that creates a lopsided thrust on the crankshaft generating awesome vibration and that is why other manufactures just won't do it.  However, that 45 degree wallop gives the Harley-Davidson that kick in the seat of the pants torque and a feel that just can't be duplicated.  Some Twin-Cam engines have internal counterbalance weights and others the engines are rubber mounted to the frame to shed the severe shaking effect that engine produces.  It may be wrong, but it ended up being right.  Just listen to the engine's explosive, crisp detonating effect from the exhaust.  No other bike has that most perfect sound millions of riders love.

13.  Many Harley-Davidson riders just accept the fact the Twin-Cam engine has its defects and is just the price to pay to ride.  You got to look at that way to ease the pain in the wallet.  The price is high, but to many the fee is worth the ride, every dollar of it.

14.  Another way to look at things is to buy a used Harley-Davidson Twin-Cam motorcycle and the money you save can be used to repair and upgrade the engine and components.

15.  Don't forget to look at the new 2012 and later Sportster models.  They have fat 16" front tires, better suspension and are way better than the earlier models by far and most of all they have none of the awful engine defects the Twin-Cam engine bikes have.  They also run cooler, are quick, sporty to ride, good gas mileage and they have that Harley sound that you like.  Test drive one!   Click on article link below on how to change oil on Harley.

  "Not all repair shops and dealers are honest.  Cheating still takes place." 

16.  Are you being shortchanged on oil changes?  You might be.  Many shops are now employing a suction oil extractor device that instead of allowing dirty oil to drain as it should from under the bike from the oil drain plug, the suction device has a metal "wand" that is inserted into the oil filling plug and the oil is vacuumed out.  Why?  Because it is wickedly fast to remove the oil from the engine, primary and transmission.  Why is it bad?  Because a lot of dirty oil remains inside the engine compartments in "pockets" that were designed to be drained out by gravity.  And to make matters worse?  You may be charged for gaskets, o-rings and labor that was never used in the oil change!  Plus, you never really know for certain the quality of the oil put into your motorcycle.  Just because you paid for synthetic oil you may have a blend or none at all as mineral oil was inserted.  You are way better off learning how to change your own oil.  Click on the link below. 

17.  You just had your bike serviced by the dealer.  There is no way you can easily tell if the oil levels in the bike are where they should be.  There are still too many instances where people drive off with their bike with no oil in the primary case or transmission!  Mistakes happen because mechanics are not doing the oil changes, inexperienced employees are often used behind closed doors where you can't observe what is really going on.  This is something you need to be aware of at Harley-Davidson dealerships.  Upon delivery of the bike you should check the oil levels, even on a brand new bike.  The primary chain case is more difficult as you need to remove the derby cover to check the oil level.  I wish it were not so, but these nightmares continue as customers bring back the bike in a destroyed condition and you can be just about certain the dealer is going to blame the problem on "mechanical failure" not "mechanic failure" and bill you a huge repair bill or even deny the warranty if you have an extended warranty (if the dealer is a bad one they will play dirty rotten tricks on their customers).  Search the Internet and you'll see what I am talking about.  Hang around dealership and repair facilities long enough and you'll see it happening.

"And if you think switching to a metric bike will solve your problems you will be sadly mistaken."

18.  With all these defects should you still buy a Twin-Cam Harley?  I say yes, but keep it under a reliable and trustworthy warranty and even then, expect a fight to keep your coverage.  Many dealers will fight you, so appeal to H-D Corporate for assistance and even they too may be reluctant to repair engine defects.  Learn to perform your own oil changes (click here) as having "others" do it for you can still void your warranty.  How?  There is no proof the quality of the oils sold was actually used.  Buy Harley-Davidson oil and filter, keep receipts and a log book and you will have closed that door solid that voids warranties despite the Magnuson Warranty Act, there are exceptions to legal protection you should be aware of.  And if you think switching to a metric bike will solve your problems you will be sadly mistaken.  Read this article:  Why You Don't Want To Buy a Japanese, Italian, German, Korean or British Motorcycle






  I often get inquires asking that if the Twin-Cam Harley-Davidson engines are defective if the older EVO (Big-Twin Evolution) engine should be bought.  My answer is a big "NO" as that engine is defective too and unreliable and that is one reason why Harley-Davidson junked the thing and created the Twin-Cam engine.  The Evo crankshaft can fail, the valve angles are so severe the push rods bend, etc.  That engine is history so leave it be.  The Twin-Cam engine is no better for all it does is trade one defect for another so it still has detrimental defects.  Frankly, it is a disaster. However, you should consider buying a S&S engine for it is beefed up and does not have the engine defects for it has been redesigned in many critical areas.  That is the route I would recommend for you can get a real big-bore engine too that will not fall apart on you.  

  If you love to ride Harley's then start learning how to fix them yourself.  Stop making excuses.  If you have to take a small engine course or a motorcycle repair school class or buy repair manuals and learn as you go.  Subscribe to V-Twin Magazine and other motorcycle magazines as they have many articles on how to fix and upgrade Harley-Davidson motorcycles.  You can start by learning how to change the oil. How to Change Oil on Harley  Then you can learn to change your own tires and save hundreds of dollars (book is forthcoming soon).  I am not saying Harley's are unreliable as they are more reliable than ever, but when an engine or transmission or frame defect arises you can fix it yourself or at least the majority of them.  I'll tell you a truth.  If you do not learn to fix the bike the bike will fix you so you have to give up riding for the cost of ownership will eventually become too much to bear.  That advice is not just for Harley-Davidson bikes, it is all motorcycles!  The cost of parts and labor is crippling rider's financial ability to pay.  Example:  It is straight-out dishonesty to charge $500 for a set of tires or to pay $350 for an oil change!  Dealers are getting rich at your expense.  Learn to do it yourself.  You can do it.  If you only knew the idiots who are actually working on your bike at the dealership you would be alarmed.  Believe me, mechanics are not changing oil or tires its the kids or parts people they pull to do those jobs.  And the horror stories taking place from these unskilled employees is frightening like delivering bikes with no oil in them, improperly installed tires, loose axles and brake calipers, etc.  It is safer to do it yourself than to blindly trust questionable characters behind closed doors in the service department.  

  Do not ever trust a mechanic or a dealership to do you right.  Be vigilant and be on high guard dealing with anyone who has the power to remove money from your wallet.  Never believe for a moment these employees, managers and owners are your "friend" for this is just "good business" to treat you with very special attention.  If you have ever run a business you know what I am talking about.  It is awful just how many people are being robbed by the repair industry.  They will lie to you with a smile on their face while shaking your hand telling you that you need expensive repairs when you don't.  It is sickening to have to write this and even more punishing to those who do not know and are victimized.  The repair community is also "close knit" so go out of town to get second opinions and the further away the better, like 100 miles.  Even then, they all know each other!  They all play the same game!  Even shops and dealers with many good referrals from riders I have found to be cheating  the majority of their customers.  They cheat so much they have no fear of exposure.  They cheat so blatantly nobody will suspect any wrongdoing.  With total arrogance they operate their price inflation scams.  They may even do fine work, but the price you pay will be higher than you bargained for, one way or another.  When you begin to work on your own bike you will begin seeing how the industry inflates simple jobs into bigger and more expensive jobs.  Buyer beware. 

  Extended Warrantee is the way to go if you ride a Twin-Cam Harley-Davidson motorcycle.  But make sure this warrantee has no deep strings attached that you "must" adhere to a strict service plan.  Here's an actual example from a H-D Dealership what such service costs using the miles accrued formula.  This is what it costs to have your bike serviced regardless of a warrantee you have.  Keep in mind the charges below are "routine maintenance" not including anything the dealer finds wrong that needs to be repaired or replaced, its a labor fee that may or may not include an oil change or replace drive belt (belt replacement costs about $750 on Twin-Cam), install new brake pads and new tires.

Twin-Cam Motorcycle

1M miles $340.

2500 miles $145.

5000 miles $340

10,000 miles $405.

20,000 miles $595.

Sportster XL Motorcycle (slightly lower cost for Sportster)

1M miles $330.

2500 miles $133.

5000 miles $330

10,000 miles $375.

20,000 miles $514.

  As you can see, it really can pay you to purchase a service manual and learn to inspect, repair, change tires and change oil yourself.  So what if it takes you five years to learn at your own pace... those five years will come and go and at least you can ride at the lowest possible cost compared to other riders who refuse to learn and end up paying for the privilege.  You are not too old to learn, just as you may not be too old to ride.  Give yourself a chance to at least do the routine maintenance chores.


1.  Question:  If you were to buy a new Twin-Cam engine Harley which model would it be?

Answer:  It would be a 96" Twin-Cam engine Road King model with cast wheels.  It is Harley-Davidson's most enduring and popular cruiser motorcycle.  It has a low price range, but has very high quality components everywhere on the motorcycle.  You can bump up the power output to exceed the 103" engine easily, that is, if you need more power.  The bike looks good, easy to customize with lots of parts available to fit this model bike.  You just can't go wrong buying a Road King.  You'll like the money you save too as the Road King cost less than other touring bikes, including Harley's own upscale touring bikes.  And, if you consider buying out of state, you can expect to shave another $3,000+ off the sales price.  There are no deals locally anymore.  In most cases you got to buy out of state to get deals.  It seems as if the local dealers hate us and only want to "gouge" the local riders.   

2.  Question:  So what is the cure if cam timing gears can not be used in the Twin-Cam engine?

Answer:  The problem with gears is that when the crankshaft webs slip out of alignment the pinion shaft will then wobble causing the gears to clash and even break.  This will occur even if your technician installed the gears perfectly.  The cure is to weld the crankpin to the two webs.  Quality aftermarket engines all have welded crankshaft webs-to pin.  This way the alignment never goes out and gear clashing just can not happen... unless crankshaft crankcase bearings wear out or fail then disaster will strike.  Quality aftermarket engines all have stronger and larger main shaft bearings installed into the crankcases to prevent this sort of failure.  As you can see, there is a fix, but it is expensive.  If you have a stock Harley engine and you install gear cam drives you are asking for big trouble down the road.  It is almost better to just replace those pesky cam chain shoes every 15,000 miles or better yet, pay the price and weld the crankpin and install stronger crankcase bearings.  Take a look at S&S engines and you will see they have made these corrections to their engines. 

3.  Question:  If I see the outer cam chain follower worn half-way down will the inner shoe be the same?

Answer:  Every Twin-Cam Harley owner should learn this one inspection.  Removing the cam cover is only a matter of removing a few screws and pulling the cover off.  Very simple.  Very easy.  Takes only fifteen minutes to remove, inspect, reinstall cover.  Do this and you can prevent your engine from seizing up.  When you remove the outer cam chest cover you will see a nylon pad rubbing on the cam chain.  If you see the pad is worn down 1/4 way, this is okay, but the inner shoe that can not be seen will be worn down 1/2 through.  It is time to replace both shoes.  This method also applies to the newer hydraulic cam chain tensioners too.  Believe me, the hydraulic cam chain tension system is an improvement, but not a cure by any means. Those shoes will still wear out and will need to be replaced or disaster will ruin your engine completely.

 4.  Question:   I was told a Twin-Cam engine can seize up even if the cam chain tension shoes are in good condition.  How can this be?

Answer: The disaster is that the cam chain tensioner shoes will wear down and the tiny particles of plastic/nylon will clog the oil pump reducing and eventually stopping oil flowing into the engine.  This will happen on the new hydraulic system too.  The engine defect of having cam chains in the Twin-Cam engine is a disaster in the making, but it makes the dealers and repair shops very happy.  

 5.  Question:  The cam chain system is so defective it has me worried sick.  How can I fix this thing?

Answer 1:  Read Question #2.  You may consider purchasing a S&S engine that has all the problems and defects fixed and swap out the stock engine.  This will cure a ton of problems.  Expensive it is, but reasonable in the end for peace of mind and enjoyment.  Before purchasing, make certain you get it in writing that the engine you buy will in fact fit the rubber mounts and fit the frame of the bike you own.  If you don't get it in writing you can get burned badly.  Sure, it may fit, but only rigidly to the frame and vibration will rattle your teeth.  Not good.  Get a guarantee of full refund, with refund of shipping fees too if the engine does not fit the frame.  Other things to consider too is the electrical connections to the engine will also be compatible. S&S is a good company to deal with and they will help you every step of the way.  But when dealing with very expensive engines, you just got to get things in writing to make sure.  Make sure it is in writing between S&S and also in writing with the repair shop that will insert the engine.  Do not trust anybody, be professional about it.  What if you get an engine that does not fit and it is a verbal agreement?  You may be out of luck and be stuck with an engine you can't use or be held hostage for expensive shipping fees to exchange the engine.  It is not cheap to ship an engine one way, often around $200 each way.

Answer 2: Many riders are worried about those pesky cam chain tensioners in the Twin-Cam engine and most believe the problem has been fixed with low pressure hydraulically operated cam chain shoe tensioners when the problem has not been solved at all.  If you have the old spring-loaded tensioners you need to inspect them as they will generally fail at 15,000 to 30,000 miles.  You can inspect the outer shoe by simply removing the cam chest cover.  The inner shoe is invisible, but it wears out twice as fast as the outer shoe.  If the outer shoe is worn down 75% the inner shoe is about ready to fail.  A Roland Sands Clarity cam cover will help a lot as you can simply look and see the outer shoe condition.  Every Twin-Cam engine should have one.  When it comes time to replace both cam chain shoes you should replace the oil pump too as the older engines with spring loaded cam chain shoes also has a defective oil pump putting out way much too low oil pressure and very poor scavenging of the crankcase.  

Answer 3:  Read about the Harley-Davidson Milwaukee-Eight engine below.  They have fixed that valve train rats nest at last!



What You Need to Know About the Harley-Davidson Milwaukee-Eight (M8) V-Twin Engine:  

  The engine was revealed in September 2016.  It has two versions in regards to piston/stroke size 107ci (1,750cc) (3.937 x 4.375 bore and stroke and is oil cooled) and a 114ci (1,870cc) (4.016 x 4.500 bore and stroke and is water cooled).  At this writing, the new engine is only available on limited touring and CVO models (but no doubt will trickle down to replace all of the Twin-Cam engine bikes).  Check with your Harley-Davidson dealer as the transitions will be constant and they can update you on availability on specific models at time evolves.  Yes, you can buy a Road King now with the new engine including the Road Glide and Electra, and other models.

  The engine has one cam with four lobes and one cam chain with one hydraulic cam chain tensioner (read below about reliability issues), two spark plugs per cylinder (one center and one on side of combustion chamber) and four valves per cylinder with an 18-pole alternator that makes plenty of electrical power even at the low 850-rpm idle that gives the engine a better laid-back idle exhaust note sound.  Throttle body is a larger 55mm bore and compression ratio is now as high as 10.5:1 delivering more torque and power over an equivalent size Twin-Cam engine.

  The engine runs cooler whether cooled by water or oil circulating by the exhaust valves.  The exhaust ports in the cylinder heads are also bridge-cooled (oil or water depending on the engine size) and the pathway to the exhaust pipe is shorter to reduce cylinder head heat. 

  The engine has a balancer inside which manages vibration to 75% and the primary chain case width has been reduced due to a smaller size hydraulic actuated clutch with an improved compensator bearings and ramp sprocket which solves many lower end problems.  Crank cases are 25% stronger.

  The 107 engine oil capacity has increased from 4 quarts to 5.2 quarts.  The 114 engine oil capacity has increased from 4 quarts to 5 quarts.  The owner's manual should answer questions regarding oil capacity.

  Engine idle was 1,050 but is now 850 rpm which creates a better loping sound and a cooler engine.

  The clutch is now hydraulic so using the clutch will be easier than ever. 

  There are two ignition coils per cylinder for more power and better fuel burn management, but you will only see two ignition coils.  Having two independent coils also allows the engine to keep on running if one coil fails (if the ECM computer will permit this redundancy).  

  The engine appearance has changed.  The cam chest cover is smaller and less square in shape and the valve covers has what appears to be "muscles" to accommodate the 4-valves in each cylinder head.  Could be this engine be nicknamed the "muscle head" engine.    

  There are three version of the engine:

Milwaukee-Eight 107 oil-cooled (107 CID, 1750cc).

Milwaukee-Eight 107 water-cooled (107 CID, 1750cc).

Milwaukee-Eight 114 water-cooled (114 CID, 1870cc).

Note: All versions of the engine still employ cooling fins and are still air-cooled.



  At this writing, the engine is so new we don't know the defects yet, but I am certain many defects have been cured and fixed as time will tell. 

Crankshaft:  We don't know if the crank webs are welded or still pressed-fit.  If welded, then the crank-slip defect will be resolved.  If not, trouble could very well be on the horizon.  The crankshaft has been totally redesigned increasing flywheel inertia 20% without adding weight.  

Pistons:  They are light weight design, flat top, with low-tension bore-conforming rings and compression ratio is higher.  The piston rods are larger and stronger.   

Camshaft:  Yes, there is a cam chain and a cam chain shoe that can wear out and cause a catastrophic engine failure.  However, like the Indian Power Stroke engine the inner cam chain and tensioner shoe is eliminated.  You can easily check the existing exterior cam chain shoe for wear simply by removing the cam cover.  If the shoe is worn, it is very easy to replace the shoe with a new one without the use of special tools. This is a wonderful improvement and for all intent and purposes the cam chain defect has been generally considered cured and fixed.  You still need to inspect the shoe condition, but even a non-mechanic can do this and even replace a worn-out shoe.  Very easy to do!   There is no need to pull the cams or oil pump to replace the shoe.  This is great news!  There is only one camshaft in the M-8 engine further simplifying the cam chest mechanics.

Lifters:  The valves are operated by solid lifters, but like the Twin-Cam engine, with a twisted operating valve train.  This may still be a problem if the cam-actuated solid lifters stick in their bores and cause pistons to strike stuck open valves.  Time will tell if the lifter problem is solved.  The engine has solid lifters which means there is an adjustment screw on the rocker arms near the valve stem.  Harley-Davidson claims the valves never need to be adjusted for the life of the engine due to the valves being light in weight so there will be no valve recession.  This is yet to be seen and proven in the real world with valve recession almost certain to occur as the valves wear against valve seats.  However, if a valve adjustment were ever needed it would be very easy to do not having to deal with engine disassembly like other engines with solid lifters or ride directly on the cam shaft lobe relying on (under or over) valve shim cups which is a royal pain to adjust the valves.  At least the M-8 engine has an adjustment screw to adjust the valves like the tappet system of old.  It would be worth your attention to periodically check the valve clearance so as not to burn a valve, say every 25,000 miles would be fine.  There could be some sort of a compensation system employed so no valve adjustments are needed?  Nobody knows at this time.  The only hint is the valves are so light in weight they will not wear the valve seat or the valve face (recession).  I find it hard to believe the factor valve adjustment will last the life of the engine.  Has Harley-Davidson created a miracle of no valve lash on solid lifters?  We'll see.  I hope it is true.

  Foreseeable Problem With Rocker Arms -  When the engine is new the lifters, pushrods, rocker arms and valve stems will work just fine.  The problem begins when the rocker arm loses stability due to uneven wear of the point of contact with the valve stems.  There's no adjustment available to compensate when one of the two intake (or exhaust) valves wear unevenly compared to the other valve (remember, one rocker arm operates two valves).  A loud tapping sound will be made with a loss of power.  The hydraulic lifter will not compensate for this unbalanced situation.  Will a valve burn?  No.  Just a tapping sound will be produced as the rocker arm slaps against the valve stem.  It's not a major problem and the tapping noise will not harm the engine.  To correct the problem?  Wait until the engine needs a top-end overhaul then reset the valves in the cylinder head, replace the rocker arms, push rods and that should bring the engine valve train back into new condition.   

Primary Drive:  The primary chain case is much more narrow which eliminates that sloppy, long-leveraged drive-side crankshaft.  Reliability will increase here, no doubt about this along with a redesigned and stronger redesigned compensator sprocket that should not fail like those in the past.  There's an automatic primary chain tensioner that has had problems in the Twin-Cam engine and could keep on tightening the chain which can cause fast chain and sprocket wear and even overheating main crankshaft and clutch roller bearings.  Need to watch for this problem if it has not been fixed.  The tensioner just keeps on tightening the chain each time you wallop the throttle upon hard acceleration like when passing a car.  The spring-loaded tensioner never loosens the chain to maintain a proper chain tension.  A hydraulic system would be a fix for this.  You may be able to install the old manual chain adjustment system (but I am not certain if this can be done on the new M-8 engine). 

Cylinder Heads:  Increased cooling fin depth keeps engine heat under control.  Exhaust ports are shorter also lowers head temperature.  Water and/or oil ports, depending on engine model, keeps the engine running cool.  Each cylinder head has two intake and two exhaust valves which flows more air and fuel for increase engine power and obtain better fuel mileage.  Two spark plugs per cylinder creates a faster and more even combustion burn (just like a top-fuel nitro dragster).  Engine has an advanced knock-sensor system that reacts faster and an automatic compression release for easy and much faster effortless engine starting even when the engine is cold.   

Breather System:  Much improved as the crankcase air flow is now directed into the transmission case instead of directly into the air cleaner.  This should stop the oil priming problem (oil spilling out of air cleaner) on all prior V-twins have historically had.  Once the pressure has bled off into the transmission case the unpressurized vapors can now be bled-off-controlled to be burned in the cylinders.  There is one potential problem as these blow-by gasses can be very acidic and transmission components could corrode creating a new problem.  Generally, I would not worry much about corrosion issues as engine/transmission oil have acid controlling alkaline chemicals to counteract the acidity.  Just keep the oil clean - especially when laid up for the winter in storage - and all should be well. 

Fixed Defects:  At this time, the engine appears to have fixes that will make the Milwaukee-Eight engine more reliable, more powerful and more fun.  But there are other problems that may be hidden from our eyes at this juncture in time.  The valve train is heavy above the lifters so there is potential for trouble of valve float or metal fatigue issues.  Cylinder heads may crack for all we know over time due to changes in the design.  Let's see what develops and hope nothing fails in the real world.  At least Harley-Davidson is addressing many of the defect problems that ruined the Twin-Cam engine.

Cam Chain Tensioner:  The cam chain will wear out the fiber composite tensioner shoe as it did to the Twin-Cam engine.  If you do not inspect the tensioner it can wear down to metal-on-metal contact with the cam chain and it will clog up the oil pump and seize the engine.  If this happens at highway speed it could kill you as it locks up the rear wheel and you fail to pull in the clutch in time.  So, the M8 engine is still defective in this regards, but the cure is simple; inspect the condition of the shoe every 30,000 miles and replace it every 60,000 miles or every 30,000 miles just to be safe.  Replacing the shoe is so easy, just remove the cam chest cover, unscrew the shoe retaining bolt, install the new shoe, reinstall the retention bolt, torque it to specification, replace the gasket and cam chest cover.  As easy as installing a new spark plug!  The old Twin Cam engine required a slew of special tools and some major assembly riders could not do on their own.  You can replace the cam chain shoe on your M8 engine easily.  Just remember one thing, if you forget and ignore inspecting of the cam chain shoe condition it will wear out and bite you hard as it catastrophically destroys your wonderful M8 engine.  Don't forget the inspections!  

Reliability:  The Milwaukee-Eight engine will never surpass the reliability of the Sportster 1200 Evolution engine for that V-twin engine is proven to be incredibly defect free.  So much so, that many Harley-Davidson dealers do not even keep an inventory of Sportster engine parts.  Imagine that!  If you need a engine or transmission part they order the parts from the factory.  Just ask any Harley dealer how many engine repairs they do on Sportsters and they will respond with a depressing answer.  They don't make money on Sportster engines breaking down.  My 2012 1200cc Sportster XL Custom has 70,000 miles on it and it runs like new.  Doesn't burn oil and sounds quiet like it was when new.  But the M-8 engine is way better than the Twin-Cam engine.  Read this article now...  Harley-Davidson Sportster 1200 & Why You Should Buy One  


  I would recommend buying a Harley-Davidson big-twin with the new Milwaukee-Eight engine even with the unknowns regarding potential engine defects - as I can see already - many of the serious defect problems have been addressed. 

  But there are still some problems that should still be considered.  One huge problem that remains is to get rid of the left-side pulley drive system that requires the entire primary chain case be disassembled just to replace a drive belt or transmission drive pulley.  Switching out the transmission to a right-hand drive would solve this problem, like the Sportster models, that takes 30 minutes or less to switch out a drive belt or pulley sprocket.

  The Milwaukee-Eight will be a big winner for Harley-Davidson and more so to the riders as many defects have been addressed.  Good-ridden to the rat's nest Twin-Cam engine!  At the first chance you can get, get this new Milwaukee-Eight engine.  You can't buy the engine and put it into your Twin-Cam frame as it will not fit.  Sorry, you got the buy the complete bike if you want the M-8 engine (unless you plan to build a custom or chopper).

  Which engine should you buy, oil or water-cooled?  Does not matter.  Nothing wrong with water-cooling except that it adds some complexity with water pump, thermostat, radiator, maintaining leaks and fluid level and fluid-change maintenance.  I would go with the oil-cooled 107CID version.  But if 114CID engine is what you need and want then you get the water-cooled engine by default.

  You can bump up the horsepower on these M-8 engines just as you can with the Twin-Cam engine.  Harley-Davidson has Screaming Eagle Performance upgrade stages ready when you are.

  The Milwaukee-Eight engine has more power than the Sportster, but the bikes they power are heavy iron cruiser machines.  If you do not need a big bagger or a Big-Twin engine, then buying a 1200CID Sportster will be your best value.  Sportsters are light in weight, have lots of power and fuel economy and you can buy two new Sportsters for the price of one upscale bagger and three or four Sportsters for one CVO Harley-Davidson!     


Click here to read our free article on How to Buy a Cruiser Motorcycle.

Harley-Davidson Sportster 1200 & Why You Should Buy One

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How to Change Oil on Harley

Harley-Davidson Bagger Motorcycle - The Insanity

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  © by James Russell.  All Rights Reserved.  Posted on: Reprint Rights:  Enthusiasts and Motorcycle Dealers may post and reprint this article and use it to help them sell motorcycles as long as they do not make any changes to the document.