Cambio de compensador de primaria: mejorando el arranque de Harley-Davidson

Primary compensator change: improving Harley-Davidson starting

The compensator is a shock absorber

Indeed, in Harley-Davidson Big Twin engines the compensator acts as a buffer between the engine pulsations, which leave the crankshaft and are transmitted through the primary chain to the transmission, passing through the clutch. A smoother ride is therefore achieved and jerks are reduced when accelerating and decelerating.

Recoil problems

Surely if you own (or know someone) of a Twin Cam 96 ”, manufactured between 2007 and 2011, the typical starting problem of these models sounds familiar to you: the engine turns, but suddenly, strange noises are heard (as if something is about to break), and the pistons recoil, blowing smoke out of the air filter.

This backlash is due precisely to the fact that an older design of the primary chain balancer is being used, which worked well in previous engines, but is not able to handle the increased mass of modern larger engines, especially during the starter, causing the crankshaft and pistons to "bounce" backwards, producing the backfire we mentioned earlier.

The solution is already invented

To minimize this problem, we can opt for 2 solutions: a more economical one, consisting of replacing the system with a compensator eliminator, as in Sportster models, and we can also install the compensator that the most modern models equip, starting in 2012.

Let's do it

We are installing a Harley-Davidson Screamin ’Eagle compensator upgrade kit.

We start by disconnecting the battery (safety, above all), and following the workshop manual, drain the oil from the primary crankcase and remove the cover from it. We have to thoroughly clean this cover inside to be able to stick the oil baffles.

These parts will direct part of the circulating oil to the critical points of the compensator, to lubricate it. We will use the glue and the clip included in the kit and we will use an instrument to apply pressure while it hardens, so that once installed it withstands extreme temperatures and vibrations.

We continue with the disassembly of the internal crankcase of the primary, which will allow us to extract the rotor from the alternator.

The rotor must be replaced because the original includes the compensator spring discs, while in the new system these are separated, facilitating service.


Once the new rotor is installed, we reassemble the internal crankcase of the primary,

compensator gear,

the spring discs and the ramp.

We assemble the chain with the new crown and its nut, which has bearings in its rear part.

We carry out the final tightening of the compensator and the clutch using a torque wrench and a special locking tool.

Now we only have to reinstall the chain tensioner, using this trick that will save us time: we compress it outside the motorcycle and fasten it with a nylon tie and, after screwing it in place, we cut the tie to release the tension.

At this point, we mount the primary cover again and fill with 1 quart (approximately 1 liter) of specific oil for primary transmission and reconnect the battery.


We can see how the boot is now done in a faster and quieter way, without bouncing. And best of all, the overall ride will be smoother and more progressive thanks to the improved throttle operation.

Frank burguera


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Tengo ese problema de arranque y me dicen que cambie el piñón de la puesta en marcha y la corona y otros que es el kit del compensador de la primaria ya no se que pensar. Podrían darme precio de dicho kit y de la corona y piñón mi moto es una fat boy del 2007 H1 americana


Mine went out after my engine was rebuilt after 2 weeks.
Very good illustration and I enjoyed reading looking at the photos.


Does my 2006 need to be up dated ? Is there any recall notices on this problemo ?

Terry Ingalls

Thank you very much for the illustration it was very good, I might need it for later use on my 08 Heritage Softail

Mike DeJaynes

Compensateur d’origine Harley CVO 110 de la merde…
Remplacer new “Man O-War” est très nickel !!!

Thierry Waldmann

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