Last year, 15,000 miles ago, I started chasing problems in the primary of my bike. It started with the typical compensator failure Harley is known for. After riding the Lake Superior circle tour in June I developed a new noise that sounded like something not fully engaging. Turns out that was a broken spring pack in the new Baker compensator. Then when riding to the Zeigler Motorsports for our last ride I had what I thought was another sound consistent with a bad compensator. Took it to my mechanic, he found the auto chain tensioner had adjusted to its maximum point and the chain was still sloppy. The teeth of the clutch basket were also worn sharp. The mechanic seemed to think the sound I was hearing when accelerating was the chain riding high on the tooth and then dropping into place. Below is a picture of my clutch basket and another of a new stock Harley clutch basket you can clearly see the difference in the teeth. I’ve also included some supporting information below.
Harley-Davidson’s automatic chain tensioners, while designed to maintain consistent tension in the primary chain, have been identified by some riders and mechanics as a potential cause of premature wear in the primary drive components. Here’s why:
1. Over-Tensioning:
Automatic tensioners apply constant pressure to the primary chain, regardless of whether it’s needed. As the chain expands and contracts during operation, the tensioner may over-tighten, putting unnecessary stress on the chain, compensator, and clutch basket. This can lead to accelerated wear on bearings, gears, and other internal components.
2. Inflexibility During Heat Cycles:
When the engine heats up, metal parts and the chain expand. A properly adjusted chain needs a little slack to account for this, but the automatic tensioner doesn’t allow the same flexibility as a manual adjustment. This can result in added stress, particularly during high RPMs or long rides, causing parts to wear faster than expected.
3. Compensator Issues:
The compensator—a key part in the primary system—absorbs drivetrain shock. An overly tight chain puts more strain on the compensator, causing it to wear out prematurely. Many riders report noise or vibration issues in the compensator as a result of the constant high tension from the automatic tensioner.
4. Limited Lubrication Flow:
An over-tightened primary chain can also affect the flow of primary oil, as tighter components may restrict how well the lubricant circulates. Without proper lubrication, the clutch and other internal parts could experience increased friction, leading to further wear.
5. Noise and Vibration Issues:
While automatic tensioners are designed to reduce chain slap, some riders experience increased noise or vibration due to the stress placed on internal parts. This can be an early indicator of wear developing in the primary drive.
To mitigate these issues, some Harley riders switch to manual chain tensioners or modify their automatic tensioners to allow more slack. Regular inspection and monitoring of the primary components are also recommended to catch wear early.
Because I ride for long periods of time at higher RPM’s, I’ve opted to switch to a manual chain tensioner made by Baker as well as replace the chain and clutch. Yeah I have to do a little more work to check the chain but having the piece of mind that it’s not over tensioned and causing more premature wear is fine with me.
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