Adjusting the chain of a motorcycle is considered to be one of the most important and regular maintenance tasks a motorcyclist can attend to. An excessively tight chain can wear out the chain, sprockets, and engine driveshaft sooner, while an excessively loose chain can jump off the rear sprocket or scrape on the swing arm during critical riding situations. Finding and setting the right amount of chain slack is essential for keeping your motorcycle in good running condition in order to prevent unnecessary wear and tear, or catastrophic failure. If you’re looking to attend to this yourself at home, or are in the mood to learn about how it should be done, here is a step-by-step guide on motorcycle chain adjustment.
Loosen the axle nut and adjuster nuts
The chain of a motorcycle is adjusted by moving the rear axle front or back. In order to allow for this movement, your axle nut, and swing arm adjuster nuts will need to be loosened while your motorcycle is on the ground for added stability. Don’t remove the nuts or bolts completely – you will need to keep these attached to the motorcycle during the entire procedure. Grab your sockets and wrenches and crack those nuts and bolts until they feel loose.
Lift the rear tire
The rear tire of the motorcycle must be lifted so that your rear wheel can spin and slide freely during the adjustment step. Lifting the rear wheel can be done through the use of a center stand which comes standard on some motorcycles, a paddock stand that lifts on the swingarm, or a center stand lifter that lifts directly from under the frame below the engine. Regardless of the method chosen, your rear wheel will need to be lifted from the ground in order to get your chain slack adjustment dialed in.
Adjust and measure
It’s now time to get your chain adjusted to specification. As mentioned previously, the chain of the motorcycle is loosened or tightened through the forward and backward movement of the rear axle respectively. When your rear axle moves forwards, your rear sprocket moves along with it, shortening the distance to the front sprocket, and the opposite is true for tightening as well.
Generally, tightening of the chain is what most riders will have to manage since over time, chains tend to loosen up a bit and will need to be adjusted accordingly. In order to do this, take a wrench or hex key to the rear swingarm adjuster, and move the axle back by tightening the adjuster slowly. In order to keep your alignment during the procedure, every adjustment on the left part of the swing arm must be done to the right or vice versa.
Don’t forget to check the chain slack of your motorcycle while working on the rear adjusters. The optimal chain slack for your respective motorcycle is best determined by your owner’s manual or a chain slack guide on the swingarm, but in general, motorcycles should maintain a healthy slack of 25 mm to 35 mm for the bottom part of the chain. You can check this by focusing on the section of the chain below the swingarm, grabbing a tape measure, and measuring the slack of the chain from its resting position to its top-most position by pressing upwards on the chain.
Tighten and recheck
Once you have ensured that both sides of the swing arm adjusters are set correctly, and that your chain slack is following the ideal measurement, you can proceed with tightening everything back together. First, tighten the swing arm adjusters until the nuts start to provide a bit of feedback. You don’t want to tighten these nuts too much, since you may risk putting your rear wheel out of alignment, or over tightening your chain.
After the rear adjusters are loosely tightened, you will need to tighten your axle bolt and nut. Grab your wrenches and tighten this section down using the recommended torque specification of your owner’s manual. After this, you can now proceed to tighten the rear adjusters and lock nuts a little bit more until your wrench provides just a bit more feedback. Afterwards, you should be good to go with a properly slacked chain and a newly aligned rear wheel.