Yamaha YFM250RX 2008 Service Manual page 71

ADJUSTING THE VALVE CLEARANCE
1
2
1
3-10
a. Turn the crankshaft counterclockwise.
b. When the piston is at the Top Dead Center
(TDC) on the compression stroke, align the
"I" mark on the AC magneto rotor with
the stationary pointer
cover.
NOTE: NOTE:
Top dead center (TDC) is a point where the
mark on the AC magneto rotor and the pointer
on the crankcase cover match, plus at the
same time, the punch mark in the camshaft
sprocket and the pointer on the cylinder head
match.
c. Measure the valve clearance with a thick-
ness gauge .
Out of specification → Adjust.
Thickness gauge
90890-03079
Narrow gauge set
YM-34483
5. Adjust:
• valve clearance
a. Loosen the locknut
b. Insert a thickness gauge between the end
of the adjusting screw and the valve stem.
c. Turn the adjusting screw
fied valve clearance is obtained.
Tappet adjusting tool
90890-01311
Six piece tappet set
YM-A5970
• Hold the adjusting screw to prevent it from
moving and tighten the locknut to specifica-
tion.
CHK
ADJ
on the crankcase
.
until the speci-
14 Nm (1.4 m•kg, 10 ft•lb)