Installing The Piston And Cylinder - Yamaha WR250F 2022 Owner's Service Manual

Piston pin outside diameter limit
15.971 mm (0.6288 in)
3. Measure:
• Piston pin bore inside diameter "b"
Out of specification  Replace the piston.
Piston pin bore inside diameter
limit
16.043 mm (0.6316 in)
b
EAM30100

INSTALLING THE PISTON AND CYLINDER

1. Install:
• Oil ring expander "1"
• Lower oil ring rail "2"
• Upper oil ring rail "3"
• Top ring "4"
TIP
Be sure to install the piston ring so that the man-
ufacturer's marks or numbers face up.
CYLINDER AND PISTON
2. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clip "3"
TIP
• Apply the engine oil to the piston pin.
• Install the piston with the mark "a" on it pointing
to its exhaust (rear) side.
• Before installing the piston pin clip, cover the
crankcase opening with a cloth to prevent the
clip from falling into the crankcase.
• Make sure that the end of the piston pin clip is
not positioned at the cutout in the piston.
5-35
4
New