Yamaha YFM50S Service Manual page 60

ADJUSTING THE VALVE CLEARANCE
NOTE:
_
• When the piston is at the Top Dead Center
(TDC) on the compression stroke, there
should be clearance between the valve stem
tips and their respective adjusting screws.
• Be sure to align the alignment mark 3 on the
camshaft sprocket with the alignment mark
4 on the cylinder head.
• If there is no clearance, rotate the crankshaft
counterclockwise one turn.
c. Measure the valve clearance using a thick-
ness gauge 5.
L LLL L LLL L L LLL L
3. Adjust:
• valve clearance
M MMM M MMM M M MMM M
a. Loosen the locknut 1.
b. Insert a thickness gauge 2 between the
adjuster end and the valve end.
c. Turn the adjuster 3 clockwise or counter-
clockwise with the tappet adjusting tool 4
until the proper clearance is obtained.
Tappet adjusting tool (3 mm)
P/N. YM-08035, 90890-01311
d. Hold the adjuster to prevent it from moving
and then tighten the locknut.
Locknut
7 Nm (0.7 m · kg, 5.1 ft · lb)
e. Measure the valve clearance.
f. If the clearance is incorrect, repeat the
above steps until the proper clearance is
obtained.
L LLL L LLL L L LLL L
3 - 9
CHK
ADJ
L LLL L L LLL L L LLL L LLL
M MMM M M MMM M M MMM M MMM
L LLL L L LLL L L LLL L LLL