Yamaha TZ250M, Owner'S Service Manual

Page: 123 / 287

CYLINDER HEAD, CYLINDER AND PISTON
4-25
ENG
2. Check:
• Piston mark
a
Piston mark
a a
(color)
A (red)
B (orange)
C (green)
*
3. Combination:
Combine the piston and cylinder by the fol-
lowing chart.
Cylinder mark Piston mark (color)
A A(red)
B B(orange)
C C (green)
(
NOTE:
When you purchase a cylinder, you cannot
designate a specific one. Choose the piston
that matches the above chart.
EC474821
Power valve
1. Inspect:
• Power valve
1
Wear/Damage
≥
Replace.
Carbon deposits
≥
Remove.
• Valve shaft
2
• Solid bush
3
• Oil seal
4
Wear/Damage
≥
Replace.
EC474901
Power valve hole on cylinder
1. Remove:
• Carbon deposits
From power valve hole surface
a
.
NOTE:
Do not use a sharp instrument. Avoid scratch-
ing the aluminum.
EC475000
ASSEMBLY AND INSTALLATION
EC475180
Power valve
1. Install:
• Power valve
1
• Bolt (power valve)
2
GT
9 Nm (0.9 m
d
kg, 6.5 ft
d
lb)
NOTE:
Install the power valve at cut-away faced
a
for
down side.