Yamaha 2002 YB50, Service Manual

Page: 63 / 161

ENG
INSPECTION AND REPAIR
4-12
4. Remove:
• Cracking marks and carbon deposits on
piston sides.
5. Inspect:
• Piston wall
Wear/striping/damage Change
6. Measure:
• Cylinder piston clearance
Steps for measuring the clearance of the
cylinder piston
First step:
• Measure the lower diameter “C” with a dial
gauge.
NOTE:
Measure the inner diameter of cylinder “C” in
parallel and at right angles to the crankshaft.
Then find the mean of the measurements.
• If this is outside the specified value, rectify
or
change the cylinder, change the piston and
the set of rings.
Second step:
• Measure the diameter of the piston skirt “P”
with a micrometer.
a
5.0 mm (0.20 in) from the inner edge of
the
piston
Wear
Standard limit
Inner diameter
40.0 mm 40.10 mm
of cylinder “C”
Taper
– 0.05 mm
“T”
Eccentricity
– 0.01 mm
“R”
“C” = Maximum D
“T” = (Maximum D
1
o D
2
) - (Maximum D
5
or D
6
)
“R” = (Maximum D
1
D
3
o D
5
) -
(Maximum D
2
D
4
o D
6
)