Yamaha 2009 YFM25RY Service Manual page 193

• Upper oil ring rail "3"
• 2nd ring "4"
• Top ring "5"
TIP
Be sure to install the piston rings so that the
"T" marks or numbers face up.
2. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clips "3"
TIP
• Apply engine oil the piston pin.
• Make sure the dot "a" on the piston points
towards the exhaust side of the cylinder.
• Before installing the piston pin clip, cover the
crankcase opening with a clean rag to pre-
vent the clip from falling into the crankcase.
3. Install:
• O-ring New
• Cylinder gasket
New
• Dowel pins
New
5-28
CYLINDER AND PISTON
4. Lubricate:
• Piston
• Piston rings
• Cylinder
(with the recommended lubricant)
Recommended lubricant
Engine oil
5. Offset:
• Piston ring end gaps
a. Top ring
b. Upper oil ring rail
c. Oil ring expander
d. Lower oil ring rail
e. 2nd ring
f. 20 mm
6. Install:
• Cylinder
TIP
• While compressing the piston rings with one
hand, install the cylinder with the other hand.
• Pass the timing chain and timing chain guide
(intake side) through the timing chain cavity.
7. Tighten:
• Cylinder bolt
Cylinder bolt
10 Nm (1.0 m·kg, 7.4 ft·lb)