Yamaha CS50 Service Manual page 76

INSPECTION AND REPAIR
a. Measure cylinder bore "C" with the cylinder
bore gauge.
NOTE:
Measure cylinder bore "C" by taking side-tosi-
de and front-to-back measurements of the
cylinder.Then, find the average of the measu-
rements.
Cylinder
bore "C"
Taper Limit
"T"
Out of round
"R"
"C" = maximum of D
"T" = maximum of D
D or D
5
"R" = maximum of D
of D
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
c. Measure piston skirt diameter "P" with the
micrometer.
k a 5 mm from the bottom edge of the piston.
Standard
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"
f. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
4-13
Standard
39.99 ~ 40.01 mm
–
–
~ D
1
, or D
1
6
, D
1 3
, D or D
2 4 6
Piston size "P"
CS50: 39.952 ~ 39.972 mm
CS50Z: 39.957 ~ 39.977 mm
Piston-to-cylinder clearance
CS50: 0.034 ~ 0.047 mm
CS50Z: 0.029 ~ 0.042 mm
<Limit>: 0.1 mm
ENG
Wear limit
40.1 mm
0.05 mm
0.01 mm
6
- maximum of
2
or D - minimum
5