Checking The Cylinders And Pistons - Yamaha YZF-R7 Owner's Service Manual

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CONNECTING RODS AND PISTONS
EB404403

CHECKING THE CYLINDERS AND PISTONS

The following procedure applies to all of
the cylinders and pistons.
1. Check:
• piston wall
• cylinder wall
Vertical scratches → Replace the
crankcases, and the piston and piston
rings as a set.
2. Measure:
• piston-to-cylinder clearance
a. Measure cylinder bore "C" with the
cylinder bore gauge.
NOTE:
Measure cylinder bore "C" by taking
side-to-side and front-to-back measure-
ments of the cylinder. Then, find the
average of the measurements.
Cylinder bore gauge
90890-03017
Cylinder bore "C"
Maximum taper
"T"
Out of round "R"
"C"= maximum of D
"T" = maximum of D
mum of D or D
5
"R" = maximum of D
mum of D , D
2
b. If out of specification, replace the
crankcases, and the pistons and pis-
ton rings as a set.
c. Measure piston skirt diameter "P"
with the micrometer.
Micrometer
90890-03008
a 10 mm (0.39 in) from the bottom edge
of the piston
Standard
d. If out of specification, replace the pis-
ton and piston rings as a set.
4 - 65
ENG
72.000 ~ 72.008 mm
(2.8346 ~ 2.8350 in)
0.05 mm
(0.0016 in)
0.05 mm
(0.0016 in)
~ D
1 6
, or D – maxi-
1 2
6
, D or D – mini-
1 3 5
or D
4 6
Piston size "P"
71.954 ~ 71.972 mm
(2.8328 ~ 2.8335 in)