Engine; Adjusting The Valve Clearance - Yamaha XT250X Service Manual

EAS20471

ENGINE

EAS20520

ADJUSTING THE VALVE CLEARANCE

The following procedure applies to all of the
valves.
NOTE:
Valve clearance adjustment should be made
G
on a cold engine, at room temperature.
When the valve clearance is to be measured or
G
adjusted, the piston must be at top dead center
(TDC) on the compression stroke.
1. Remove:
Fuel tank
G
Refer to "FUEL TANK" on page 6-1.
2. Remove:
Intake tappet cover "1"
G
Exhaust tappet cover "2"
G
Camshaft sprocket cover "3"
G
1
3
3. Remove:
Spark plug cap
G
Spark plug
G
4. Remove:
Timing mark accessing screw "1"
G
Crankshaft end cover "2"
G
5. Measure:
Valve clearance
G
Out of specification → Adjust.
Valve clearance (cold)
Intake
Exhaust
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
a. Turn the crankshaft counterclockwise.
b. When the piston is in the compression stroke,
align camshaft sprocket mark "a" with cylin-
der head mark "b". This is the Top Dead Cen-
ter (TDC).
c. Make sure that generator rotor mark "c"
aligns with generator rotor cover mark "d".
2
d. Measure the valve clearance using special
thickness gauge "1".
Out of specification → Adjust.
Special thickness gauge
3-5
ENGINE
0.05–0.10 mm (0.0020–0.0039 in)
0.10–0.15 mm (0.0039–0.0059 in)
90890-01399
1