Yamaha YZ450F, Owner'S Service Manual

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INSP
ADJ
VALVE CLEARANCE ADJUSTMENT
3. Remove:
• Timing plug
1
• Straight plug
2
• O-ring
4. Check:
• Valve clearance
Out of specification
→
Adjust.
Valve clearance (cold):
Intake valve:
0.10 ~ 0.15 mm
(0.0039 ~ 0.0059 in)
Exhaust valve:
0.20 ~ 0.25 mm
(0.0079 ~ 0.0098 in)
Checking steps:
• Turn the crankshaft counterclockwise with
a wrench.
• Align the T.D.C. mark
a
on the rotor with
the align mark
b
on the crankcase cover
when piston is at T.D.C. on compression
stroke.
NOTE:
In order to be sure that the piston is at Top
Dead Center, the punch mark
c
on the
exhaust camshaft and the punch mark
d
on
the intake camshaft must align with the cyl-
inder head surface, as shown in the illustra-
tion.
• Measure the valve clearance
e
using a
feeler gauge
1
.
NOTE:
Record the measured reading if the clear-
ance is incorrect.