A motorcycle chain transfers the power from the engine to the rear wheel. It is very important for the longevity of the chain and sprockets on a dirt bike to keep the chain adjusted properly. A chain that is too tight will put a strain on the chain, sprockets, and even the bike's transmission and engine, resulting in a broken chain at minimum. A chain that is too loose will slap around and hit the swing arm and wear out the sprockets prematurely. Even a high-quality chain will stretch after repeated use and will need periodic adjustment.
Things You'll Need
- Ratchet strap
- Ruler or measuring tape
- Adjustable wrench
- Cotter pin
Compress the rear suspension of the motorcycle until the chain is extended to its limit. Do this by hooking both ends of a ratcheting tie down strap onto the rear sprocket--wrap the strap over the seat. Tighten the ratchet on the strap until the bike's rear axle, the swing arm pivot point and the front chain sprocket are in a plane with each other.
Check the deflection in the middle of the chain at the top. Make sure there is about 3/4 inch of travel in the chain by measuring with a ruler while you move the chain up and down by hand.
Adjust the chain in subsequent steps if the deflection is more than 3/4 of an inch.
Straighten the cotter pin on the rear axle nut with a pair of pliers. Remove the pin with the pliers and discard it. Loosen the rear axle nut slightly with an adjustable wrench.
Loosen the lock nuts on the chain adjustment bolts on each side of the swing arm near the rear axle nut with an adjustable wrench. Turn the adjustment bolts an equal number of times on each side to tighten the chain.
Tighten the lock nuts on the chain adjusters with an adjustable wrench once you have reached a deflection in the chain of 3/4 of an inch. Tighten the rear axle nut with an adjustable wrench, Make sure one of the holes in the axle nut line up with the hole in the axle shaft. Insert a new cotter pin into the hole and bend the protruding end of the pin up against the axle shaft to keep the pin from backing out of the hole.
Remove the ratcheting tie down strap by pressing the release button and unhooking the ends from the rear sprocket.
Tips & Warnings
- When replacing your chain, consider upgrading to a longer-lasting "O" ring chain. An "O" ring chain keeps the chain lubricant internal to the chain and keeps you from having to spray messy lubricant on the outside of the chain.
- How Tight Should My Dirt Bike Chain Be?
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