Yamaha YFM660FS, Supplementary Service Manual

Page: 246 / 478

4 - 33
ENG
CYLINDER AND PISTON
REMOVING THE PISTON
1.Remove:
●
Piston pin clips
1
●
Piston pin
2
●
Piston
3
NOTE:
●
Put identification marks on each piston head
for reference during reinstallation.
●
Before removing each 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
.
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, as shown in the illustration.
Piston pin puller:
P/N. YU-01304, 90890-01304
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
*****************************************************
Measurement steps:
1st step:
●
Measure the cylinder bore “C” with a cylinder
bore gauge
1
.
a
50 mm (2.0 in) from the top of the cylinder