Yamaha YZ125 Owner's Manual

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CHAIN DRIVE4-29EAM20104CHAIN DRIVEEAM30075REMOVING THE DRIVE CHAIN1. Use a maintenance stand to raise the rearwheel off the ground.WARNINGEWA13120Securely support the vehicle so that there isno danger of it falling over.2. Remove:• Master link clip• Master link “1”• Master link plate “2”• Drive chain “3”EAM30076CHECKING THE DRIVE CHAIN1. Measure:• 15-link section of the drive chainOut of specification  Replace the drivechain.a. Measure the length “a” between the innersides of the pins and the length “b” be-tween the outer sides of the pins on a 15-link section of the drive chain as shown inthe illustration.b. Calculate the length “c” of the 15-link sec-tion of the drive chain using the followingformula.Drive chain 15-link section length “c” =(length “a” between pin inner sides +length “b” between pin outer sides)/2TIP• When measuring a 15-link section of the drivechain, make sure that the drive chain is taut.• Perform this procedure 2–3 times, at a differentlocation each time.2. Check:• Drive chainStiffness  Clean, lubricate, or replace.3. Clean:• Drive chaina. Wipe the drive chain with a clean cloth.b. Put the drive chain in kerosene and re-move any remaining dirt.c. Remove the drive chain from the keroseneand completely dry it.4. Check:• Drive chain roller “1”Damage/wear  Replace the drive chain.• Drive chain side plate “2”15-link length limit242.9 mm (9.56 in)123G089068G088937G088938G088939G088940