Yamaha 20C Service Manual page 150

POWR
INSPECTION
Inspection
1) Using a micrometer, measure the piston diam-
eter at right angles to the piston-pin centreline,
10 mm (0.4 in) above the bottom edge.
Piston diameter:
66.955 – 66.980 mm
(2.6360 – 2.6370 in)
2) Using the measured cylinder bore diameter in
thrust directions, subtract the piston diameter
measurement from the cylinder bore diameter
measurement.
Piston clearance:
0.040 – 0.045 mm
(0.0016 – 0.0018 in)
If this clearance is greater than the maximum,
replace all pistons to standard or oversize,
and/or rebore all cylinders.
Oversize piston:
67.25 mm (2.6476 in)
67.50 mm (2.6575 in)
5-18
E