Yamaha YZF-R25 Service Manual page 105

5. Measure:
• Valve clearance
Out of specification → Adjust.
Valve clearance (cold)
Intake
0.11–0.18 mm (0.0043–0.0071 in)
Exhaust
0.21–0.30 mm (0.0083–0.0118 in)
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a. Turn the crankshaft counterclockwise.
b. Position the marks "a" on the generator rotor
on both sides of the slots "b" in the generator
rotor cover.
c. Position the punch mark "c" on the balancer
drive gear "1" between the projections "d" on
the timing chain guide (lower side) "2".
d
c
1
TIP
When the alignment mark "e" on the intake cam-
shaft sprocket and the alignment mark "f" on the
exhaust camshaft sprocket are aligned with the
edge "g" of the cylinder head, piston #1 is at 90°
ATDC.
e
g
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b
a
2
f
PERIODIC MAINTENANCE
d. Measure the valve clearance with a thickness
gauge "1".
▼▼▼
1
TIP
• If the valve clearance is incorrect, record the
measured reading.
• Measure the valve clearance in the following
sequence.
Valve clearance measuring sequence
Cylinder #1 → #2
A. Front
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6. Remove:
• Camshaft
TIP
• Refer to "CAMSHAFTS" on page 5-11.
• When removing the timing chain and cam-
shafts, fasten the timing chain with a wire to re-
trieve it if it falls into the crankcase.
7. Adjust:
g
• Valve clearance
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a. Remove the valve lifter "1" and the valve pad
"2" with a valve lapper "3".
3-6
Thickness gauge
90890-03180
Feeler gauge set
YU-26900-9
#2 #1
A
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