Checking The Piston Rings - Yamaha Grizzly550 User Manual

Bore
92.000–92.010 mm (3.6220–
3.6224 in)
(YFM5FGY/YFM5FGPY)
102.000–102.010 mm (4.0157–
4.0161 in)
(YFM7FGY/YFM7FGPY)
Wear limit
92.080 mm (3.6252 in)
(YFM5FGY/YFM5FGPY)
102.080 mm (4.0189 in)
(YFM7FGY/YFM7FGPY)
Taper limit
0.05 mm (0.002 in)
Out of round limit
0.05 mm (0.002 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 cylinder,
and replace the piston and piston rings as a
set.
c. Measure piston skirt diameter D "a" with the
micrometer.
Diameter D
91.955–91.970 mm (3.6203–
3.6209 in)
(YFM5FGY/YFM5FGPY)
101.955–101.970 mm (4.0140–
4.0146 in)
(YFM7FGY/YFM7FGPY)
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.
6
- maximum of D
2 5
or D - minimum of
3 5
5-30
CYLINDER AND PISTON
• Piston-to-cylinder clearance =
Cylinder bore "C" -
Piston skirt diameter "D"
Piston-to-cylinder clearance
0.030–0.055 mm (0.0012–0.0022
in)
Limit
0.10 mm (0.0039 in)
(YFM5FGY/YFM5FGPY)
0.13 mm (0.0051 in)
(YFM7FGY/YFM7FGPY)
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
set.
L LLL L LLL L L LLL L L LLL L
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.
Top ring
Ring side clearance
0.030–0.070 mm (0.0012–0.0028
in)
Limit
0.12 mm (0.0047 in)
2nd ring
Ring side clearance
0.020–0.060 mm (0.0008–0.0024
in) (YFM5FGY/YFM5FGPY)
0.030–0.070 mm (0.0012–0.0028
in) (YFM7FGY/YFM7FGPY)
Limit
0.12 mm (0.0047 in)
(YFM5FGY/YFM5FGPY)
0.13 mm (0.0051 in)
(YFM7FGY/YFM7FGPY)
Oil ring
Ring side clearance
0.04–0.13 mm (0.0016–0.0051 in)
(YFM5FGY/YFM5FGPY)
0.060–0.150 mm (0.0024–0.0059
in) (YFM7FGY/YFM7FGPY)
L LLL L L LLL L LLL
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