Yamaha 2004 YXR660 Service Manual page 77

ADJUSTING THE VALVE CLEARANCE
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3 - 4
7. Remove:
• engine cooling fan 1
8. Remove:
• timing plug 1
9. 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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a. Turn the crankshaft counterclockwise with a
wrench.
b. Align the "I" mark 1 on the rotor with the
stationary pointer 2 on the A.C. magneto
cover. When the "I" mark is aligned with the
stationary pointer, the piston is at the Top
Dead Center (TDC).
NOTE:
• When the piston is at the Top Dead Center
(TDC) 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.
c. Measure the valve clearance using a thick-
ness gauge 3.
L LLL L LLL L L LLL L L LLL L
CHK
ADJ
M MMM M M MMM M MMM
L LLL L L LLL L LLL