Adjusting your bike’s chain won’t make it any faster, but it’s critical if you want your chain to last. It’s fast, easy, and next to checking your own tire pressure it’s one of the first things any home mechanic should learn. Too tight is as bad as too loose, but it’ll only take minutes to get it right. You should check and adjust your chain every 500 miles (805 km), and more often for a dirt bike. It’s also a great time to look for kinks or rust, and to give your chain a quick cleaning and lubrication, too.
Step 1 Read the owner’s manual for the correct amount of drive-chain slack. Most streetbikes also have a sticker on the swingarm.
Step 2 With the engine off, put the bike on its sidestand or centerstand, and shift the transmission into neutral.
Step 3 Find the midway point of the chain between the front and rear sprockets . Push up on the bottom of the chain and note the distance between the full-slack (lower) position and the no-slack (upper) position on the bottom . 1.2–1.6 inches (30–40 mm) is typical for streetbikes, while dirt bikes may need 1.4–2.0 inches (35–50 mm) of slack.
Step 4 To adjust the drive chain, loosen the axle nut a couple of turns . If all you have is a short wrench, you can stand on it to get the nut loose.
Step 5 Most streetbikes and some dirt bikes feature bolts that you turn to increase or decrease the chain slack. Adjust them a quarter turn at a time; be sure you make the same adjustment on each side of the swingarm, so the rear wheel stays aligned . Measure and adjust until your chain is within spec.
Step 6 Whatever system you have, when you have the correct chain tension, remember to tighten the axle nut back to the correct torque (check your manual, but usually to 65 foot-pounds or 88 newton-meters).