Checking The Piston Rings - Yamaha Vmax VMX17C 2009 Service Manual

1. Check:
• Piston wall
• Cylinder wall
Vertical scratches → Replace the upper
crankcase, and replace the piston and piston
rings as a set.
2. Measure:
• Piston-to-cylinder clearance
M MMM M MMM M M MMM M M MMM M
a. Measure cylinder bore "C" with the cylinder
bore gauge.
TIP
Measure cylinder bore "C" by taking side-to-side
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.
Bore
90.000–90.010 mm (3.5433–
3.5437 in)
Taper limit
0.050 mm (0.0020 in)
Out of round limit
0.050 mm (0.0020 in)
"C" = maximum of D –D
1
"T" = maximum of D or D
1
or D
6
"R" = maximum of D , D
1
D , D or D
2 4 6
b. If out of specification, replace the upper
crankcase, and replace the piston and piston
rings as a set.
c. Measure piston skirt diameter "D" "a" with the
micrometer.
Piston
Diameter D
89.960–89.975 mm (3.5417–
3.5423 in)
CONNECTING RODS AND PISTONS
M MMM M M MMM M MMM
6
- maximum of D
2 5
or D - minimum of
3 5
5-83
b. 10 mm (0.39 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"
Piston-to-cylinder clearance
0.025–0.050 mm (0.0010–0.0020
in)
Limit
0.10 mm (0.0039 in)
f. If out of specification, replace the upper
crankcase, piston, and piston rings as a set.
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EAS24430

CHECKING 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 clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
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