Yamaha FJR13AG, Service Manual

Page: 417 / 784

CONNECTING RODS AND PISTONS
5-88
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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.
b. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
set.
c. Measure piston skirt diameter “P” with the mi-
crometer.
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.
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
set.
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EAS30748
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.
Bore
79.000–79.010 mm (3.1102–
3.1106 in)
Taper limit
0.050 mm (0.0020 in)
Out of round limit
0.050 mm (0.0020 in)
“C” = maximum of D
1
, D
2
, D
3
, D
4
, D
5
, D
6
Taper (front-to-back) = maximum difference be-
tween D
1
, D
3
, D
5
Taper (side-to-side) = maximum difference be-
tween D
2
, D
4
, D
6
Out of round (top) = difference between D
1
, D
2
Out of round (middle) = difference between D
3
,
D
4
Out of round (bottom) = difference between D
5
,
D
6
Diameter
78.965–78.980 mm (3.1089–
3.1094 in)
a. 5 mm (0.20 in) from the bottom edge of the
piston
• Piston-to-cylinder clearance =
Cylinder bore “C” -
Piston skirt diameter “P”
Piston-to-cylinder clearance
0.020–0.045 mm (0.0008–0.0018
in)
Piston ring
Top ring
Side clearance limit
0.120 mm (0.0047 in)
2nd ring
Side clearance limit
0.120 mm (0.0047 in)
a
P