Checking The Piston Pin; Installing The Piston And Cylinder - Yamaha WR450FN 2022 Owner's Service Manual

b. Upper of cylinder
EAM30099

CHECKING THE PISTON PIN

1. Check:
• Piston pin
Blue discoloration/grooves  Replace the
piston pin and then check the lubrication sys-
tem.
2. Measure:
• Piston pin outside diameter "a"
Out of specification  Replace the piston pin.
Piston pin outside diameter limit
17.981 mm (0.7079 in)
3. Measure:
• Piston pin bore inside diameter "b"
Out of specification  Replace the piston.
Piston pin bore inside diameter
limit
18.045 mm (0.7104 in)
b
EAM30100

INSTALLING THE PISTON AND CYLINDER

1. Install:
a
• Oil ring expander "1"
• Lower oil ring rail "2"
• Upper oil ring rail "3"
• 2nd ring "4"
• Top ring "5"
TIP
b
Be sure to install the piston rings so that the
manufacturer's marks or numbers face up.
2. Install:
• Piston "1"
• Piston pin "2"
• Piston pin clip "3"
TIP
• Apply 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
CYLINDER AND PISTON
New