Yamaha YFM660FS, Supplementary Service Manual

Page: 161 / 478

3 - 14
CHK
ADJ
ADJUSTING THE VALVE CLEARANCE
6.Remove:
●
Timing plug
1
7.Check:
●
Valve clearance
Out of specification
→
Adjust.
Valve clearance (cold):
Intake:
0.10 ~ 0.15 mm
(0.0039 ~ 0.0059 in)
Exhaust:
0.15 ~ 0.20 mm
(0.0059 ~ 0.0079 in)
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Checking steps:
●
Turn the crankshaft counterclockwise with a
wrench.
●
Align the “I” mark
1
on the rotor with the sta-
tionary pointer
2
on the crankcase cover.
When the “I” mark is aligned with the station-
ary pointer, the piston is at the Top Dead
Center (T.D.C.).
NOTE:
●
When the piston is at the Top Dead Center
(T.D.C.) on the compression stroke, there
should be clearance between the valve stem
tips and their respective rocker arm adjusting
screws.
●
If there is no clearance, rotate the crankshaft
counterclockwise one turn.
●
Measure the valve clearance using a feeler
gauge
3
.
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