Yamaha XT660R S Service Manual page 275

CYLINDER AND PISTON
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2. Measure:
• piston-to-cylinder clearance
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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
D or D
5 6
"R" = maximum of D
mum of D , D or D
2 4
b. If out of specification, replace the cylinder
and the piston and piston rings as a set.
c. Measure piston skirt diameter "P" with the
micrometer.
a 10 mm (0.39 in) from the bottom edge of the pis-
ton
d. If out of specification, replace the piston and
piston rings as a set.
e. Calculate the piston-to-cylinder clearance
with the following formula.
Piston-to-cylinder clearance =
Cylinder bore "C" -
Piston skirt diameter "P"
Piston-to-cylinder clearance
0.030 ~ 0.055 mm
(0.0012 ~ 0.0022 in)
<Limit>: 0.13 mm (0.0051 in)
f. If out of specification, replace the cylinder
and the piston and piston rings as a set.
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ENG
M MMM M M MMM M M MMM M
100.000 ~ 100.010 mm
(3.9370 ~ 3.9374 in)
0.05 mm (0.002 in)
0.05 mm (0.002 in)
~ D
1 2
or D – maximum of
1 2
, D or D – mini-
1 3 5
6
L LLL L L LLL L L LLL L
MMM
LLL