Yamaha PW50W 2007, Service Manual

Page: 106 / 168

ENG
5-13
CYLINDER HEAD, CYLINDER AND PISTON
“C”= maximum of D
1
–D
6
“T”= (maximum of D
1
or D
2
)-(maximum of D
5
or D
6
)
b. If out of specification, replace the cylinder,
and replace the piston and piston rings as
a set.
c. Measure piston skirt diameter “D” with the
micrometer.
a
5 mm (0.20 in) from the bottom edge of the piston
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 “D”
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as
set.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Diameter D
39.952-39.972 mm (1.5729-1.5737 in)
Piston-to-cylinder clearance
0.034-0.047 mm (0.0013-0.0019 in)
Limit
0.10 mm (0.0039 in)
CHECKING THE PISTON RINGS
1. Measure:
9
Piston ring side clearance
Out of specification
→
Replace the piston
and piston rings as a set.
NOTE:
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
Piston ring side clearance
Ring side clearance
0.020-0.060 mm (0.0008-0.0024 in)
Limit
0.080 mm (0.0032 in)
5PG-7-10 104 06.5.16, 17:43:51