Removing The Cylinder And Piston; Checking The Cylinder And Piston - Yamaha XT660Z 2008 Service Manual

EAS00253
REMOVING THE CYLINDER AND
PISTON
1. Remove:
• Piston pin clips "1"
• Piston pin "2"
• Piston "3"
CAUTION:
Do not use a hammer to drive the piston pin
out.
2
3
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
crankcase.
• Before removing the piston pin, deburr the
piston 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
2. Remove:
• Top ring
• 2 nd ring
• Oil ring
1
5-27
CYLINDER AND PISTON
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.
EAS00255
CHECKING THE CYLINDER AND
PISTON
1. Check:
• Piston wall
• Cylinder wall
Vertical scratches → Replace the cylinder
and the piston and piston rings as a set.
2. Measure:
• Piston-to-cylinder clearance
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure cylinder bore "C" with the cylinder
bore gauge.
NOTE:
Measure cylinder bore "C" by taking side-to-
side and front-to-back measurements of the
cylinder. Then, find the average of the mea-
surements.
Cylinder bore "C"
Taper limit "T"
Out-of-round "R"
"C" = maximum of D
"T" = maximum of D
of D or D
5 6
"R" = maximum of D
minimum of D , D
2 4
100.000-100.010 mm
(3.9370-3.9374 in)
0.050 mm (0.002 in)
0.050 mm (0.002 in)
~ D
1 2
or D – maximum
1 2
, D or D –
1 3 5
or D
6