Engine; Adjusting The Valve Clearance - Yamaha XG250 Service Manual

EAS20470

ENGINE

EAS20520

ADJUSTING THE VALVE CLEARANCE

The following procedure applies to all of the
valves.
NOTE:
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
●
Left side cover
●
Right side cover
●
Left fuel tank side cover
●
Right fuel tank side cover
●
Refer to "GENERAL CHASSIS" on page 4-1.
Fuel tank
●
Refer to "FUEL TANK" on page 6-1.
Spark plug cap
●
Spark plug
●
Cylinder head side cover1 "1"
●
Cylinder head side cover2 "2"
●
Cylinder head side cover3
●
Refer to "CYLINDER HEAD" on page 5-5.
2
2. Remove:
Straight screw plug "1"
●
Center cap "2"
●
1
2
3. Measure:
Valve clearance
●
Out of specification → Adjust.
Valve clearance (cold)
Intake
0.05–0.10 mm (0.0020–0.0039 in)
Exhaust
0.10–0.15 mm (0.0039–0.0059 in)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the crankshaft counterclockwise.
b. When the piston is at TDC on the compres-
sion stroke, align the punch mark "a" in the
camshaft sprocket with the stationary "b" on
the cylinder head.
c. Align the TDC mark "c" on the pickup coil ro-
tor with the stationary pointer "d" on the
crankcase cover.
d
c
1
d. Measure the valve clearance with a thick-
ness gauge "1".
Out of specification → Adjust.
3-3
ENGINE
b
a
1