Yamaha YFM660RN Service Manual page 179

SWINGARM AND DRIVE CHAIN
2.Check:
Drive chain
Stiffness → Clean and lubricate or replace.
3.Clean:
Drive chain
***********************************************
Wipe the drive chain with a clean cloth.
Put the drive chain in kerosine and remove
any remaining dirt.
Remove the drive chain from the kerosine
and completely dry it.
CAUTION:
This machine has a drive chain with small
rubber O-rings 1 between the drive chain
side plates. Never use high-pressure water
or air, steam, gasoline, certain solvents
(e.g., benzine), or a coarse brush to clean
the drive chain. High-pressure methods
could force dirt or water into the drive
chain's internals, and solvents will deterio-
rate the O-rings. A coarse brush can also
damage the O-rings. Therefore, use only
kerosine to clean the drive chain.
***********************************************
4.Check:
O-rings 1
Damage → Replace the drive chain.
Drive chain rollers 2
Damage/wear → Replace the drive chain.
Drive chain side plates 3
Cracks/damage/wear → Replace the drive
chain.
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