Removing The Piston; Checking The Timing Chain Guide; Checking The Cylinder And Piston - Yamaha YFM4FAR Service Manual

CYLINDER AND PISTON

REMOVING THE PISTON

1.Remove:
Piston pin clips 1
G
Piston pin 2
G
Piston 3
G
NOTE:
Before removing piston pin, deburr the clip
groove and pin hole area. If the piston pin
groove is deburred and the piston pin is still
difficult to remove, use the piston pin puller 4.
Piston pin puller set:
P/N. YU-01304, 90890-01304
CAUTION:
Do not use a hammer to drive the piston
pin out.
2.Remove:
Piston rings
G
NOTE:
Spread the end gaps apart while at the same
time lifting the piston ring over the top of the
piston crown.

CHECKING THE TIMING CHAIN GUIDE

1.Check:
Exhaust side timing chain guide
G
Wear/damage → Replace.

CHECKING THE CYLINDER AND PISTON

1.Check:
Cylinder and piston walls
G
Vertical scratches → Rebore or replace the
cylinder and the piston.
Cylinder water jacket
G
Mineral deposits/rust → Eliminate.
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ENG