Checking The Piston Rings - Yamaha V Star 950 Service Manual

Bore = maximum of D
1
Wear limit = maximum of D
Out of round limit = maximum of D
minimum of D or D
2 4
a. 10.0 mm (0.39 in)
b. 85.6 mm (3.37 in)
A. Intake side
B. Exhaust side
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
c. Measure the piston skirt diameter "D" "a"
with the micrometer.
Piston
Diameter D
84.955–84.970 mm (3.3447–
3.3453 in)
b. 8 mm (0.31 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.
–D
4
or D
1 3
or D -
1 3
CYLINDERS AND PISTONS
• Piston-to-cylinder clearance =
Cylinder bore "C" -
Piston skirt diameter "D"
Piston-to-cylinder clearance
0.030–0.055
0.0022 in)
Limit
0.15 mm (0.0059 in)
f. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
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EAS24430

CHECKING THE PISTON RINGS

The following procedure applies to all of the
piston rings.
1. Measure:
• Piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
TIP
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
Piston ring
Top ring
Ring side clearance
0.040–0.080
0.0032 in)
Limit
0.130 mm (0.0051 in)
2nd ring
Ring side clearance
0.030–0.070
0.0028 in)
Limit
0.130 mm (0.0051 in)
5-34
mm (0.0012–
mm (0.0016–
mm (0.0012–