Removing The Piston; Checking The Cylinder And Piston - Yamaha YXR70FX Service Manual

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CYLINDER AND PISTON
EBS00247

REMOVING THE PISTON

1. Remove:
• piston pin clips 1
• piston pin 2
• piston 3
TIP:
_
• Before removing the piston pin clips, cover
the crankcase opening with a clean rag to
prevent the piston pin clips from falling into
the crankcase.
• Before removing the piston pin, deburr the
piston pin clip grooves and the piston pin
bore area. If both areas are deburred and the
piston pin is still difficult to remove, remove it
with the piston pin puller set 4.
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
NOTICE
_
Do not use a hammer to drive the piston
pin out.
2. Remove:
• piston rings
TIP:
_
Spread the end gaps apart while at the same
time lifting the piston ring over the top of the
piston crown, as shown in the illustration.
EBS00249

CHECKING THE CYLINDER AND PISTON

1. Check:
• piston wall
• cylinder wall
Vertical scratches → Rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
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ENG