Savage Roads

Friday, July 26, 2013

Harley Drive Train "Compensator Blues"

Harley Drive Train Compensator Blues

Posted on 23. Jul, 2013 by  in Panman's Garage

It started out as a loud ticking noise. This went on for a couple of years, no one really taking too much notice. After all, Harley-Davidson is well known for having a primary drive system that sounds like a freight train is passing, right? But it didn’t stop there.Riding cross country, I always seem to be especially tuned to hearing unusual noises from my bike. A tick here, a clunk there. But when you put them all together, you finally realize that you have been riding with the Harley drive train compensator blues.
worn compensatorBefore long, it became harder and harder to start, especially when warm. Loud belches of unburned fuel spewing from the fuel body should have been a good indication of something wrong. But not a single mechanic diagnosed the problem.
One day I came across a posting on The gentleman described his hard starting and knocking noises, and then gave the answer to the problem. A bad or worn compensator.
primary The compensator is the drive mechanism located on the end of the engine main shaft, transferring the engine rotation by way of the primary chain to the clutch basket and transmission. It provides for a smooth transfer of the power to the transmission and takes up any shocks from the transmission to the engine.
Knowing that I was nearing my peak riding season (daily rider, but summer I take longer trips), I decided that I would just replace it with a Screaming Eagle compensator. After a little research, I decided on the Screaming Eagle because it is suppose to be 7x stronger than the stock compensator. This would not surprise me at all!
The Screaming Eagle compensator came with all the parts necessay for installation, and clear instructions.
Stock Harley compensator
Stock Harley compensator
Going through the parts and instructions, it became clear that I would need to take off both the outer primary cover and the inner primary cover in order to replace the stator magnet that comes with the kit. Cute how Harley started putting a ridge inside the inner primary that prevents you from removing the stator magnet without first removing the inner primary cover!
As it turned out, it was a good thing that I did need to remove the inner primary cover. In order to do so, I had to remove the clutch basket. That is where I found an unexpected problem.
clutch basketA couple of years ago, I replaced the main shaft bearing to my transmission. When I did this, I found the belt hub splines were all delaminating. As it was told to me, A Harley vendor failed to properly heat treat a large batch of these hubs. Harley put out a service bulletin to the techs, but the general public was pretty much on their own.
Well turns out, this same vendor also made the clutch basket for Harley. And you guessed it, it is not properlydelaminated splinesheat treated either. What I found was the splines inside the clutch basket were also delaminating. Pieces of splines were falling out of the clutch basket all over the ground. Just wonderful!
After another parts run to the local dealer, I was able to get a replacement clutch basket for replacement. Like I said, good thing I found it. It would have been a bear to find the problem as I crossed over the Rockies on my way to Sturgis!
Screaming Eagle compensatorClutch basket back together, I installed the springs and sprocket to the compensator. Just looking at the compensator tells you it is far more heavy duty. It is heavier, with huge plate springs and a large spline gear adaptor that slides over the main shaft. The stock compensator has just a few large splines that the chain gear rides on. On the stock unit, these splines were badly damaged, allowing the compensator to rock back and forth. The Screaming Eagle compensator has a much superior spline shaft arrangement that I believe will eliminate this problem.
Aside from running for parts, the total job was done in less that 3 hours. Not to bad!! And then off to road test.compensator assembled
The first thing I noticed was the bike was once again smooth at low speed. No more jerking that had to be controlled by feathering the clutch. As I rolled down the boulevard, the power transfer seemed a lot smoother. But when I started onto the freeway, that is when it showed it’s strength. Power transfer was immediate and smooth. Gone were the sounds of the familiar freight train. And shifting, especially down shifting, was a lot smoother and without the customary “clunk”.
Starting while hot was now no longer a problem. She cranked over easily, and no longer back fires when starting. I am relieved that problem is resolved!
If you are experiencing loud noises from your primary, hard starting when hot, and strange vibrations or hard shifting, I highly recommend that you take a good look at your compensator. And I believe that you will eliminate the Harley Drive Train Compensator Blues with a Screaming Eagle compensator.
Posted on 23. Jul, 2013 by  in Panman's Garage


  1. Harley has known about this problem for years, they even offered SE comp sprockets as a remedy for bikes with the "problem" if you were under warrenty, if you were out of warrenty, it became "YOUR problem", just another Motor Company bend over and we'll thank you.
    When mine went 2 months after warrenty, I became such a thorn in their side of my dealer, they relented and fixed the problem.