Motorcycle chain squeaking and coming off

Chain squeaking and slipping almost always point to insufficient lubrication or improper tension. The first thing to check is how tight the chain is. On a motorcycle, it should have minimal slack - you usually check the play in the middle between the sprockets with a feeler gauge. If the chain is too loose, it bounces around and can slip off under load. If it's too tight, it'll squeak and wear out quickly. Tension is adjusted with bolts on the rear wheel, but before you do that, make sure the wheel axle isn't bent.

The second reason is lack of lubrication. You need to clean and lubricate the chain periodically with a special chain lube, not just any oil. A dried-out, dirty chain makes an unpleasant noise and wears fast, plus the links stick to the sprocket teeth, which creates play. If you've neglected it for a while, try thoroughly washing the chain (kerosene or a special chain cleaner works), then dry it and treat it with chain lube.

If the problem persists after tensioning and lubing, it could be wear on the sprockets themselves or the chain links - then you need a replacement. But in most cases, it's just a matter of adjusting the tension and cleaning with lubrication.