Motorcycles with chain drive systems need regular maintenance. Most manufacturer's recommend checking the chain tension every 500 miles. Loose, tight, worn, or unlubricated chains can result in accidents. Correctly tensioned chains also improve performance of the bike on the road. Chains should be adjusted while taking into account the balance of the rear wheel to the front wheel, which, if out of balance, can damage sprockets and depreciate performance.
Put the bike up onto its centre stand with the engine off. If the bike does not have its own centre stand, stands such as the Steel Horse swingarm stand are available. The chain can be tightened when the bike is on the side stand but a centre stand allows you to judge balance of the rear wheel better. Differences in slack can also be a problem when adjusting a chain using the side stand compared to a centre stand.
Place newspaper or cardboard under the chain and then clean the chain and sprockets. Chain lubricant sprays are available which will cling to the chain and prevent fling onto the back wheel and disc brakes. Avoid getting any onto the brakes or to other parts of the bike as chain lubricants are sometimes sticky. Let the cleaner soak for a few minutes. Manually run the chain by spinning the back wheel slowly and use a rag to rub the chain clean. Chains should always stay lubricated so make sure after cleaning that it runs smoothly.
Measure the slack in the chain. The manufacturer's manual should have a section on the correct tension limits for the chain. Measurement should be made midway between the countershaft and the rear sprocket by pulling down the lower chain, pressing up on the top chain section and measuring the gap between two opposite chain rivets. Turn the back wheel and repeat this process at several points along the chain to ensure the chain is uniformly stretched. A chain with points of different stretch needs to be replaced. If the measurement is within limits, you do not need to adjust the chain or only make slight adjustments.
Check your rear wheel alignment with the front of the bike. This can be done by eye or by placing string horizontally around the bottom of the front tire and stretching it back to the rear wheel. The string acts as a line of sight. Wheel balance can be judged by how equal the distance of string to bike is on each side.
Loosen the axle nut slightly. There are chain adjusters on either side of the axle. Loosen the adjuster locking nuts and turn the adjusters until the rear wheel is in balance and the chain appears at the correct tension. Re-lock the adjusters with the locking nuts. Tighten the axle nut, and replace the locking pin (if your axle nut has one) with a new pin. Lubricate the chain while spinning the back wheel slowly. Check chain tension again. Recheck locking nuts before driving.
Replace sprockets at the same time as old chains for best performance. Chains stretch over time. To check if a chain needs replacing, pull it back from the rear sprocket. If it shows more than half of the sprocket tooth, it has become worn.
Do not overtighten a chain as this can result in the chain snapping due to the pressure. Do not allow a chain to become too loose as it can slip off the sprockets and cause an accident.