Yamaha WR250F 2016 Owner's Service Manual page 263

TIP
• Apply the engine oil to the piston pin.
• Install the piston with the F mark "a" on it
pointing to its intake (front) side.
• Before installing the piston pin clip, cover the
crankcase opening with a cloth to prevent the
clip from falling into the crankcase.
• Install the piston pin clips, so that the clip ends
are 3 mm (0.12 in) "c" or more from the cutout
in the piston.
1
a
2
3. Lubricate:
• Piston
• Piston rings
• Cylinder
4. Offset:
• Piston ring end gap
a
15
d
a. Top ring
b. Upper oil ring rail
c. Oil ring expander
d. Lower oil ring rail
3
c
3
15
15
b
c
CYLINDER AND PISTON
5. Install:
• Cylinder gasket
• Dowel pin
• Cylinder
Cylinder bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
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.
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New