Yamaha R1 Series 2015, Service Manual

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CONNECTING RODS AND PISTONS
5-74
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.
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
o
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” = average of D
1
, D
2
, D
3
, D
4
, D
5
, D
6
Taper (front-to-back) = maximum difference
between D
1
, D
3
, D
5
Taper (side-to-side) = maximum difference
between 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
Piston
Diameter
78.961–79.994 mm (3.1087–
3.1494 in)
a. 8.0 mm (0.31 in) from the bottom edge of the
piston
Piston-to-cylinder clearance = Cylinder bore “C” -
Piston skirt diameter “P”
Piston-to-cylinder clearance
0.006–0.049 mm (0.0002–0.0019
in)
Piston ring
Top ring
Ring side clearance
0.030–0.065 mm (0.0012–0.0026
in)
Limit
0.115 mm (0.0045 in)
2nd ring
Ring side clearance
0.020–0.055 mm (0.0008–0.0022
in)
Limit
0.115 mm (0.0045 in)
a
P