Yamaha YZFR1W 2007, Service Manual

Page: 272 / 429

CRANKSHAFT
5-72
NOTE:
Identify the position of each crankshaft journal
upper bearing so that it can be reinstalled in its
original place.
EAS24390
CHECKING THE CYLINDER AND PISTON
1. Check:
• Piston wall
• Cylinder wall
Vertical scratches
→
Rebore or replace the
cylinder, and replace the piston 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.
NOTE:
Measure cylinder bore “C” by taking side-to-
side and front-to-back measurements of the
cylinder. Then, find the average of the mea-
surements.
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
c. Measure piston skirt diameter “P” with the
micrometer.
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, rebore or replace the
cylinder, and replace the 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.
NOTE:
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
Bore
77.000–77.010 mm (3.0315–
3.0319 in)
Wear limit
77.060 mm (3.0339 in)
Taper limit “T”
0.050 mm (0.0020 in)
Out of round limit “R”
0.050 mm (0.0020 in)
“C” = maximum of D
1
–D
2
“T” = maximum of D
1
or D
2
- maximum of D
5
or D
6
“R” = maximum of D
1
, D
3
or D
5
- minimum of
D
2
, D
4
or D
6
Piston size “P”
Standard
76.975–76.990 mm (3.0305–
3.0311 in)
a. 12 mm (0.47 in) from the bottom edge of
the piston
Piston-to-cylinder clearance =
Cylinder bore “C” -
Piston skirt diameter “P”
Piston-to-cylinder clearance
0.010–0.035 mm (0.0004–
0.0014 in)
Limit
0.120 mm (0.0047 in)