Checking The Piston Rings - Yamaha R1 Series 2015 Service Manual

block, and replace the pistons and piston
rings as a set.
2. Measure:
• Piston-to-cylinder clearance
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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.
Then, find the average of the measurements.
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" = average of D , D
1
Taper (front-to-back) = maximum difference
between D , D , D
1 3 5
Taper (side-to-side) = maximum difference
between D , D , D
2 4 6
Out of round (top) = difference between D
Out of round (middle) = difference between D
D
4
Out of round (bottom) = difference between D
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 "P" with the mi-
crometer.
Piston
Diameter
78.961–79.994 mm (3.1087–
3.1494 in)
, D , D , D , D
2 3 4 5 6
, D
1
CONNECTING RODS AND PISTONS
a
a. 8.0 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.
Piston-to-cylinder clearance = Cylinder bore "C" -
Piston skirt diameter "P"
f. If out of specification, replace the cylinder,
and replace the piston and piston rings as a
2
set.
,
3
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,
5
EAS30748

CHECKING THE PISTON RINGS

1. Measure:
• Piston ring side clearance
Out of specification
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.
Piston ring
Top ring
2nd ring
5-74
P
Piston-to-cylinder clearance
0.006–0.049 mm (0.0002–0.0019
in)
Replace the piston
Ring side clearance
0.030–0.065 mm (0.0012–0.0026
in)
Limit
0.115 mm (0.0045 in)
Ring side clearance
0.020–0.055 mm (0.0008–0.0022
in)
Limit
0.115 mm (0.0045 in)