Removing The Piston; Checking The Cylinder And Piston - Yamaha 2004 YXR660 Service Manual

CYLINDER AND PISTON

REMOVING THE PISTON

1. Remove:
• piston pin clips 1
• piston pin 2
• piston 3
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
P/N. YU-01304, 90890-01304
CAUTION:
Do not use a hammer to drive the piston
pin out.
2. Remove:
• piston rings
NOTE:
Spread the end gaps apart while at the same
time lifting the piston ring over the top of the
piston crown.

CHECKING THE CYLINDER AND PISTON

1. Check:
• cylinder and piston walls
Vertical scratches → Rebore or replace the
cylinder and the piston.
2. Measure:
• piston-to-cylinder clearance
M MMM M MMM M M MMM
1st step:
a. Measure the cylinder bore "C" with a cylin-
der bore gauge 1.
a 50 mm (2.0 in) from the top of the cylinder
NOTE:
Measure cylinder bore "C" in parallel to and at
right angles to the cylinder matching surface.
Then, find the average of the measurements.
4 - 34
ENG
M M MMM M M MMM M M MMM M MMM