Yamaha YZ250 2022, Owner'S Service Manual

Page: 174 / 274

CYLINDER HEAD, CYLINDER AND PISTON
5-12
TIP
First tighten the power valve link lever bolt, and
then tighten the pulley bolts.
6. Check:
•
Power valve 1 smooth movement
Unsmooth movement

Repair or replace.
7. Install:
•
O-ring “1”
• Side holder “2”
•
Side holder screw “3”
• YPVS breather hose “4”
TIP
•
Apply the lithium-soap-based grease on the O-
rings.
•
Install the side holder with its projection “a” fac-
ing upward.
8. Install:
• Gasket (power valve cover) “1”
•
Power valve cover “2”
• Power valve cover screw “3”
TIP
•
Install the gasket with its cut “a” facing down-
ward and the seal print side toward the power
valve cover.
• Install the power valve cover so that the arrow
mark “b” faces upward.
EAM30554
INSTALLING THE PISTON AND CYLINDER
1. Install:
• Piston ring “1”
TIP
•
Take care not to scratch the piston or damage
the piston ring.
•
Align the piston ring gap with the pin “2”.
• After installing the piston ring, check the
smooth movement of it.
Side holder screw
4.0 N·m (0.40 kgf·m, 3.0 lb·ft)
Ne w
T
R
.
.
3
1
3
1
a
2
3
4
2
a
3
Power valve cover screw
4.0 N·m (0.40 kgf·m, 3.0 lb·ft)
Ne w
T
R
.
.