Yamaha YFM25RY Automobile User Manual


 
ENGINE
3-4
EAS20472
ENGINE
EAS20520
ADJUSTING THE VALVE CLEARANCE
The following procedure applies to all of the
valves.
TIP
Valve clearance adjustment should be made
on a cold engine, at room temperature.
When the valve clearance is to be measured
or adjusted, the piston must be at top dead
center (TDC) on the compression stroke.
1. Remove:
Seat
Front fender
Fuel tank
Refer to “GENERAL CHASSIS” on page
4-1.
Refer to “FUEL TANK” on page 6-1.
2. Remove:
Spark plug cap
Spark plug
Cylinder head side cover 1 “1”
Cylinder head side cover 2 “2”
3. Remove:
Timing mark accessing screw “1”
Crankshaft end accessing screw “2”
4. Measure:
Valve clearance
Out of specification Adjust.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the crankshaft counterclockwise.
b. When the piston is at TDC on the compres-
sion stroke, align the mark “a” on the
pickup coil rotor with the stationary pointer
“b” on the left crankcase cover.
c. Align the mark “c” on the camshaft sprocket
with the stationary pointer “d” on the cylin-
der head.
d. Measure the valve clearance with a thick-
ness gauge “1”.
Out of specification Adjust.
Valve clearance (cold)
Intake valve
0.05–0.10 mm (0.0020–0.0039
in)
Exhaust valve
0.10–0.15 mm (0.0039–0.0059
in)
Thickness gauge
90890-03180
Feeler gauge set
YU-26900-9