Yamaha YFM70RY Service Manual page 223

2. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clips "3"
TIP
• Apply engine oil onto the piston pin.
• Make sure the punch mark "a" on the piston
points towards the exhaust side of the cylinder.
• Before installing the piston pin clips, cover the
crankcase opening with a clean rag to prevent
the clips from falling into the crankcase.
1
a
3. Install:
New
• Cylinder gasket
• Dowel pins
4. Lubricate:
• Piston
• Piston rings
• Cylinder
(with the recommended lubricant)
Recommended lubricant
Engine oil
5. Offset:
• Piston ring end gaps
e
120˚
d
45˚
a. Top ring
b. Oil ring expander
c. Upper oil ring rail
d. Lower oil ring rail
e. 2nd ring
A. Exhaust side
New
2
3 New
a
120˚
b
120˚
90˚
c
45˚
A
CYLINDER AND PISTON
6. Install:
• Cylinder "1"
• Timing chain guide (exhaust side)
TIP
• While compressing the piston rings with one
hand, install the cylinder with the other hand.
• Pass the timing chain and timing chain guide
(exhaust side) through the timing chain cavity.
1
7. Install:
• Cylinder bolts "1"
TIP
Lubricate the cylinder bolt "1" threads and mat-
ing surface with engine oil.
8. Tighten:
• Cylinder bolts "1"
• Cylinder bolts (timing chain side) "2"
Cylinder bolt
1st
15 Nm (1.5 m·kg, 11 ft·lb)
2nd
50 Nm (5.0 m·kg, 36 ft·lb)
Cylinder bolt (timing chain side)
10 Nm (1.0 m·kg, 7.2 ft·lb)
1
E
5-30
2
1
E
2