Yamaha YFM660RN Service Manual page 97

ADJUSTING THE DRIVE CHAIN SLACK
3.Measure:
Drive chain slack a
Out of specification → Adjust.
Drive chain slack:
30 ~ 45 mm (1.18 ~ 1.77 in)
4.Adjust:
Drive chain slack
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Adjustment steps:
Loosen the hub nuts 1.
Loosen the locknuts 2.
Turn both adjusting bolts 3 in direction a or
b until the specified drive chain slack is
obtained.
Direction a
Direction b
NOTE:
To maintain the proper axle alignment, adjust
both sides evenly. (There are marks c on
each side of hub.)
CAUTION:
Excessive chain slack will overload the
engine and other vital parts; keep the slack
within the specified limits.
If the chain slack cannot be adjusted, replace
the sprockets and drive chain as a set.
Tighten the hub nuts and locknuts.
Hub nut:
90 Nm (9.0 m • kg, 65 ft • lb)
Locknut (chain puller):
16 Nm (1.6 m • kg, 11 ft • lb)
NOTE:
The chain should be cleaned and lubricated
after every use of the machine.
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CHK
ADJ
Drive chain slack is
reduced.
Drive chain slack is
increased.