So you’re thinking of buying a Harley-Davidson with a Twin Cam engine?
Great! There is a reason why Harley Davidson motorcycles are so popular. They’re stylish, they sound amazing, and they are very fun to ride.
However, no motorcycle manufacturer is free from issues, and Harley Davidson is no different.
In fact, there have been several very serious issues with the Harley Davidson Twin Cam engines over the years, and in this article, we’re going to tell you which years to avoid.
The Worst Harley Twin Cam Years To Avoid
Before we talk about the worst Twin Cam years to avoid, please remember this when reading the article:
We’re not trying to scare you off from buying a used Twin Cam, and the issues that you will see below are not as common as they might seem at first. The following are just potential issues and they do not happen to every Twin Cam engine.
All engines, including those made by Honda, Yamaha, Suzuki, etc., have unique problems and so does Harley Davidson. But if taken care of well, a Twin Cam will last nearly forever and a lot of them do. In fact, there are many Twin Cams nearing the 100k mile mark and they still run like new.
1999 – 2006: Camshaft Chain Tensioner Failure
Harley Davidson introduced the Twin Cam engine in 1999, and it quickly became their most popular engine.
However, it wasn’t long before problems started to arise with some Twin Cam engines.
One of the most serious issues was with the cam chain tensioners.
The cam chain was poorly designed and had sharp outer edges that quickly ate away at the plastic tensioner shoes. Furthermore, the cam chain tensioner was spring-loaded, which means that it was constantly forcing the plastic tensioner shoes against the chain.
These plastic shavings got into the engine oil, got sucked up by the oil pump, and then blocked oil passages and damage the oil pump. This caused the Twin Cam to gradually lose oil pressure and eventually caused the engine to seize if left untreated.
Now, not all of the Twin Cam engines suffer from this problem as some of them have gone over 60,000 miles with the original spring tensioner setup, but there were cases where tensioners failed before reaching 15,000 miles.
Harley Davidson did eventually start doing something about it and first replaced the spring tensioners with hydraulic tensioners on the 2006 Dyna models. By 2007, all twin cam models had the new hydraulic cam chain tensioners installed and the issue was fixed.
At this point, most of the early pre-2007 Twin Cam Harley’s have the hydraulic cam chain tensioner upgrade installed, and therefore should be perfectly fine to purchase. If you’re planning to buy a Harley with the pre-2007 Twin Cam, be sure to ask the seller for proof that the hydraulic cam chain tensioner upgrade is installed on the bike. Otherwise, you will have to do the upgrade yourself, and it does cost quite a bit.
2003 – 2006: High Crank Runout
Other Twin Cam years to avoid is the 2003 – 2006 period.
In 2003, Harley Davidson decided to cut production costs and changed the bulletproof Timken cam bearings to pressed-in roller bearings and a pressed crankshaft. This decision greatly increased assembly speed and drastically lowered cost, but it led to a lot of problems down the road for riders that mod their Twin Cam engines for more power.
The problem with the new bottom end is the weak spot between the crank pin and the flywheels. What happens is the whole crank assembly goes out of truth, and the crank becomes too unbalanced to run.
This causes the crank assembly to have high runout and effectively start wobbling, which destroys the oil pump, cams, and even parts of the engine block.
Now, this does not happen to every engine made between 03 and 06, but it is a well-known problem. It also seems to happen to stage 2 and stage 3 Twin Cam engines, as the extra HP and torque from the performance upgrades make the high runout problem worse.
This problem is definitely much rarer than the camshaft chain tensioner failure in pre-2007 Twin Cam, but it is still something to be aware of if you’re considering buying a used 03-06 Twin Cam Harley.
Be sure to ask the seller if they have experienced any high runout issues with their bike and if they have had the crank replaced.
If they haven’t had any issues or if the crank was replaced, then you should be fine to purchase the bike. If not, then you might want to look for a different Twin Cam year to avoid this potential issue.
Also Read: The Best Twin Cam 88 Performance Upgrades
Well, that’s about it – these are the most problematic Harley Twin Cam years to avoid!
Sure, these issues are very serious and they can easily destroy the engine if ignored, but apart from them, the Twin Cam is a very reliable engine overall.
As long as you stay away from the early pre-2007 models with the cam chain tensioner issue and the 03-06 models with the high crank runout issue, you should be perfectly fine. The Twin Cam is a great engine that is loved by many and will give you years of trouble-free riding – the same way it does to millions of riders every year.
Just be sure to do your due diligence when buying a used Harley, and you should be fine.
Jake is the site’s primary contributor.
Motorcycles and automotive repair have been a big part of his family for generations, therefore it’s only natural that he decided to become a heavy-duty diesel tech.
Outside of work, you’ll find Jake restoring and riding rare street bikes and ATVs.