Cylinders And Pistons; Removing The Piston; Checking The Cylinders And Pistons - Yamaha XV19SX(C) Service Manual

EAS24380

REMOVING THE PISTON

1. Remove:
• Piston pin clips "1"
• Piston pin "2"
• Piston "3"
ECA13810
CAUTION:
Do not use a hammer to drive the piston pin
out.
NOTE:
• Before removing the piston pin clip, cover the
crankcase opening with a clean rag to prevent
the piston pin clip from falling into the crank-
case.
• For reference during installation, put an identi-
fication mark on each piston crown.
• Before removing the piston pin, deburr the pis-
ton pin clip's groove and the piston's 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
3
2
2. Remove:
• Top ring
• 2nd ring
• Oil ring
NOTE:
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 cyl-
inders and pistons.
1. Check:
• Piston wall
• Cylinder wall
2. Measure:
• Piston-to-cylinder clearance
M MMM
a. Measure cylinder bore "C" with the cylinder
NOTE:
Measure cylinder bore "C" by taking side-to-side
1
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.
"C" = maximum of D
"T" = maximum of D
or D
"R" = maximum of D
D
2
5-49

CYLINDERS AND PISTONS

Vertical scratches → Rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
M MMM M M MMM M M MMM M
bore gauge.
Bore
100.000–100.010 mm (3.9370–
3.9374 in)
Taper limit
0.050 mm (0.0020 in)
Out of round limit
0.050 mm (0.0020 in)
–D
1 6
or D
1
6
, D
1 3
, D or D
4 6
M MMM M M MMM M MMM
- maximum of D
2 5
or D - minimum of
5