Harley-Davidson engines may each have their own fanbase, but what they all have in common is that they are roaring V-twins, producing a thunderous sound and sporting iconic silhouettes.
They’ve all had their ups and downs, though, and the Twin Cam engines are no exception to this.
Produced by Harley from 1998 to 2017, the Twin Cam engine replaced the Evolution engine and was designed with an increase in both power and reliability in mind.
Between 1999 and 2006, some Twin Cam issues were more notorious than others. Still, they’re all worth knowing about so you can make an informed decision when shopping for your new Harley.
1. 1999–2006 Twin Cam Troubles
One of the biggest issues with the Twin Cam was the cam chain tensioners.
H-D used plastic tensioner shoes, and these would quickly get worn down by the sharp edges of an arguably poorly designed cam chain. The matter wasn’t helped by the use of spring-loaded tensioners that kept pressure on the tensioner, forcing it against the chain and aggravating the disintegration.
The tensioners falling apart meant the plastic shavings would catch in the engine oil, be sucked up by the oil pump, cause blockages, and eventually damage the pump.
Any sort of oil pressure loss as a result caused engines to seize if the issue wasn’t resolved right away. Reports of engine failure at just 15,000 miles circulated as a direct result of the cam chain tensioner problems.
By 2006, the Dyna models received new hydraulic cam chain tensioners, which eliminated the issue. Harley also rolled out an upgrade for the affected models where riders could get the new hydraulic tensioners to replace the original plastic ones.
How to Avoid the Cam Chain Tensioner Issue
The simple answer is to buy a model after 2006, one equipped with hydraulic tensioners.
Alternatively, if you’re looking for a pre-2007 Twin Cam model, just be sure to ask the current owner for proof that the upgrade was done and the plastic tensioners have been replaced.
You can, of course, pay for the upgrade yourself, but this is an expensive option and is one you will have to factor into your purchasing budget. The average upgrade to hydraulic cam chain tensioners costs between $1,200–$2,000, inclusive of parts and labor.
Some mechanics have suggested that doing a gear drive replacement is the ultimate resolution to ensure your Twin Cam engine doesn’t encounter any issues. However, this is a costly job and it may be easier and certainly cheaper for riders to just avoid buying a bike produced before 2007.
2. 2003–2006 Twin Cam Crank Problems
Harley decided they needed to reduce production costs, so that meant the bulletproof tried and tested Timken cam bearings were swapped for pressed-in roller bearings and a new pressed crankshaft.
Assembly speed increased and production costs lowered, but a new set of problems emerged, particularly for riders who wanted to unleash the true potential of the engine with performance modifications.
The new bottom end was a weak spot between the crank pin and flywheels, meaning the crank could become too unbalanced to run. Essentially, this meant the crank assembly had high runout; it would wobble, and, ultimately, this could cause problems with the oil pump, cams, and whole engine block.
When riders did a Stage 2 or Stage 3 modification to their bikes for extra power and torque, the performance mods would make the high runout worse and exacerbate the problem.
How to Avoid High Crank Runout and Its Consequences
Not all Twin Cam engines during 2003–2006 suffered from these problems, but the best way to avoid it is to simply avoid these years.
You can also ask the previous owner if they have had any crank issues, what work they have had done, if any, and if the crank has been replaced. If the problem was resolved with a new crank, then, in theory, you should have nothing to worry about.
3. Twin Cam 88 and 96 Compensator Issues
A compensator is a small device that sits at the front of the Twin Cam 88 engine. It is there to keep the engine running smoothly by compensating for temperature and altitude changes.
Over time, it can become blocked up with debris from the road, which leads to it malfunctioning. Rough idling, more engine vibrations, and general poor performance are symptoms of a blocked compensator.
This issue wasn’t as widespread as the cam chain tensioners, but it is something Twin Cam 88 owners experienced and also later on with the Twin Cam 96.
How to Avoid the Compensator Issue
It is also an easy issue to deal with by simply keeping the compensator clean. The worst case would be that you’d need to replace the defective compensator, but parts are readily available, fairly cheap, and easy to install.
4. Twin Cam Cooling System Failures
A more general problem with the Twin Cam engines is that they had some cooling issues.
The cooling system, if not properly maintained, could lead to engine damage. If you think your engine is overheating, don’t hesitate to take the bike to a mechanic and have them check it over, it is always better to be safe than sorry.
How to Avoid Cooling System Failures
A popular cost-effective solution is to simply fit a fan to the side of the engine to aid cooling.
It is very important to note that not all Twin Cam engines were affected by the problems we’ve mentioned. Some model years were more affected than others.
Twin Cam Harleys are very popular, and this simply wouldn’t be the case if they were no good. However, for potential buyers that want to avoid any major issues or repairs, looking at models produced after 2007 is the best bet.
What is a Twin Cam engine?
The Twin Cam V-twins replaced the Evolution engine and were first introduced in 1998, after development started in the early 90s. The Twin Cam 88 debuted in 1998 with a displacement of 88 cu./1450cc. The Twin Cam 96, 96 cu./1584cc was released for the 2007 model year. Other Twin Cam engines were the 95, 103 and 110, all named after their displacement.
The idea behind the new engine was to produce a more powerful, free flowing, and reliable V-twin, taking the best bits of the Evo engine and building on it for an ultimately better result.
Twin Cams share some characteristics with the Evo engine and earlier engines, such as the traditional V-twin 45° (mostly) air-cooled design and actuated valves with pushrods.
The main difference between the two literally comes from the “twin cams” that drive the valvetrain.
What Harley models have a Twin Cam engine?
The Dyna and Softail ranges were equipped with the Twin Cam engine between 1998 and 2017.
Here’s a list of Twin Cam models:
- Fatboy FLSTF
- Low Rider FXLR
- Softail Slim FLS
- Softail Deluxe FLSTN
- Softail Heritage FLST
- Street Bob FXBB
- Super Glide FXD
- Wide Glide FXDWG
- Road King FLHR
Are Harleys with Twin Cam engines any good?
The Harley Twin Cam engines are widely regarded as some of the best motors that H-D has produced. They improved on the popular Evo engines and despite early teething issues, the Twin Cam motors went from strength to strength.
Further reading: Are Harley’s reliable?