Yamaha YB50 Service Manual page 63

INSPECTION AND REPAIR
4. Remove:
• Cracking marks and carbon deposits on
piston sides.
5. Inspect:
• Piston wall
Wear/striping/damage
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.
Inner diameter
of cylinder "C"
Taper
"T"
Eccentricity
"R"
"C" = Maximum D
"T" = (Maximum D
"R" = (Maximum D
• 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.
k
5.0 mm (0.20 in) from the inner edge of
a
the
piston
4-12
Standard
40.0 mm
–
–
o D ) - (Maximum D
1 2
or D )
6
D o D
1 3 5
(Maximum D D o D
2 4
ENG
Change
Wear
limit
40.10 mm
0.05 mm
0.01 mm
5
) -
)
6