Yamaha Star XVS950A 2009, Service Manual

Page: 225 / 402

CYLINDERS AND PISTONS
5-34
EAS24380
REMOVING THE PISTONS
The following procedure applies to all of the
pistons.
1. Remove:
• Circlips “1”
• Piston pin “2”
• Piston “3”
ECA13810
Do not use a hammer to drive the piston
pin out.
TIP
• Before removing the circlips, cover the crank-
case opening with a clean rag to prevent the
circlips from falling into the crankcase.
• Before removing the piston pin, deburr the
circlips’ groove and the piston’s pin bore
area. If both areas are deburred and the pis-
ton pin is still difficult to remove, remove it
with the piston pin puller set “4”.
2. Remove:
• Top ring
• 2nd ring
• Oil ring
TIP
When removing a piston ring, open the end
gap with your fingers and lift the other side of
the ring over the piston crown.
EAS24410
CHECKING THE CYLINDERS AND PISTONS
The following procedure applies to all of the
cylinders and pistons.
1. Check:
• Piston wall
• Cylinder wall
Vertical scratches
→
Rebore or replace
the cylinder, and replace the piston and
piston rings as a set.
2. Measure:
• Piston-to-cylinder clearance
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the cylinder bore with the cylinder
bore gauge.
TIP
Measure the cylinder bore by taking side-to-
side and front-to-back measurements of the
cylinder. Then, find the average of the mea-
surements.
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
Bore
85.000–85.010 mm (3.3465–
3.3468 in)
Wear limit
85.100 mm (3.3504 in)
Out of round limit
0.050 mm (0.0020 in)
Bore = maximum of D
1
–D
4
Wear limit = maximum of D
1
or D
3
Out of round limit = maximum of D
1
or D
3
-
minimum of D
2
or D
4