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Chain & Sprockets Harley-Davidson FXR

#maintenance #repair #tuning #harley

5 years ago

To customize the Harley-Davidson FXR 1994 for stunt riding we installed a kit of sprockets and chain. The main reason is lower transmission losses: about 12–15% for a belt versus less than 2% for a chain. Also, a chain does not stretch and has a better torque response, which is important for sensitive throttle control. A chain can be replaced without disassembling the primary chaincase. We have chosen a kit with the highest ratio to maximize torque and a strong 530-pitch chain with black-coated links. Replacement is not simple and requires removing the primary chaincase, the rear wheel and the swingarm if you want to keep the belt. It's better to use new tab washers and gaskets when assembling. If you reuse the old ones, inspect them for cracks, since the tabs can break off and damage the mechanism. We haven’t changed them since the engine is for testing and is going to be rebuilt several times or even changed. If it leaks, that's not a problem.

When adjusting chain slack, it's easiest to unbolt the shocks so the swingarm can move freely. But we have already installed new shocks using a thread lock and didn’t want to remove them. With non-standard shocks, you can't rely on the manual's procedure, so it's better to go through the full process. If there is too little slack, the chain stretches quickly. We took the slack value from the manual and it looks reasonable: a higher value is not needed and a smaller one is risky since there is a lack of precision in setting the swingarm.

This bike has an Evolution V-twin engine but the configuration is non-standard: per the manual, the primary chaincase attaches to the gearbox with 3 internal bolts, while ours has 2 internal and 1 external. The bike in the video was crashed and burned, and recovered from different parts. Though it doesn’t change much.