Checking The Drive Chain - Yamaha YFM70RY Service Manual

EAS23441

CHECKING THE DRIVE CHAIN

1. Measure:
• 15-link section of the drive chain
Out of specification → Replace the drive
chain.
15-link length limit
239.3 mm (9.42 in)
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a. Measure the length "a" between the inner
sides of the pins and the length "b" between
the outer sides of the pins on a 15-link section
of the drive chain as shown in the illustration.
b. Calculate the length "c" of the 15-link section
of the drive chain using the following formula.
Drive chain 15-link section length "c" =
(length "a" between pin inner sides + length
"b" between pin outer sides)/2
TIP
• When measuring a 15-link section of the drive
chain, make sure that the drive chain is taut.
• Perform this procedure 2–3 times, at a different
location each time.
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2. Clean:
• Drive chain
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a. Wipe the drive chain with a clean cloth.
b. Put the drive chain in kerosene and remove
any remaining dirt.
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c. Remove the drive chain from the kerosene
and completely dry it.
ECA14290
NOTICE
• This motorcycle 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 sol-
vents (e.g., benzine), or a coarse brush to
clean the drive chain. High-pressure meth-
MMM
ods 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
kerosene to clean the drive chain.
• Do not soak the drive chain in kerosene for
more than ten minutes, otherwise the O-
rings can be damaged.
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3. Check:
• O-rings "1"
Damage → Replace the drive chain.
• Drive chain rollers "2"
Damage/wear → Replace the drive chain.
• Drive chain side plates "3"
LLL
Cracks/damage/wear → Replace the drive
chain.
MMM
4-64
CHAIN DRIVE
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