Yamaha YFZ450S 2003 Service Manual page 81

ADJUSTING THE VALVE CLEARANCE
EX IN
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a. Turn the crankshaft counterclockwise.
b
b. When the piston is at the Top Dead Center
(TDC) on the compression stroke, align the
a
"I" mark a on the A.C. magneto rotor with
the stationary pointer b on the A.C. mag-
neto cover.
NOTE:
_
• In order to be sure that the piston is at the
Top Dead Center (TDC) the punch mark c
on the exhaust camshaft sprocket and the
punch mark d on the intake camshaft
sprocket must align with the cylinder head
mating surface, as shown in the illustration.
• The Top Dead Center (TDC) on the com-
pression stroke can be found when the cam-
shaft lobes are turned away from each other.
c. Measure the valve clearance with a thick-
ness gauge 1.
NOTE:
_
If the valve clearance is incorrect, record the
measured reading.
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5. Remove:
• intake camshaft
• exhaust camshaft
NOTE:
_
• Refer to "CAMSHAFTS" in chapter 4.
• When removing the timing chain and cam-
shafts, fasten the timing chain with a wire to
retrieve it if it falls into the crankcase.
3 - 9
CHK
ADJ
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