Yamaha XP500, Service Manual

Page: 133 / 559

3 - 12
CHK
ADJ
ADJUSTING THE VALVE CLEARANCE
7. Measure:
• valve clearance
Out of specification
→
Adjust.
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a. Turn the crankshaft counterclockwise.
b. When piston #1 is at TDC on the compres-
sion stroke, align the “I” mark
a
on the A.C.
magneto rotor with the stationary pointer
b
on the A.C. magneto cover.
NOTE:
• TDC on the compression stroke can be
found when the camshaft lobes are turned
away from each other.
• In order to be sure that the piston is at TDC,
the alignment mark
c
on the intake cam-
shaft sprocket and the alignment mark
d
on
the exhaust camshaft sprocket must align
with the cylinder head mating surface as
shown in the illustration.
c. Measure the valve clearance with a thick-
ness gauge
1
.
NOTE:
• If the valve clearance is incorrect, record the
measured reading.
• Measure the valve clearance in the following
sequence.
d. Turn the crankshaft 360° counterclockwise
and check the valve clearance of piston #2.
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Valve clearance (cold)
Intake valve
0.15 ~ 0.20 mm
(0.0059 ~ 0.0079 in)
Exhaust valve
0.25 ~ 0.30 mm
(0.0098 ~ 0.0118 in)
Thickness gauge
90890-03079, YM-34483
b
a
1