Yamaha YZ426F, Owner'S Service Manual

Page: 182 / 633

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INSP
ADJ
VALVE CLEARANCE ADJUSTMENT
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.
NOTE:
Squeezing the decompressor lever allows
the crankshaft to be turned easily.
●
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.