Yamaha Scorpio, Service Manual

Page: 109 / 300

4 - 32
ENG
CYLINDER AND PISTON
YP******
PISTON AND PISTON PIN INSPECTION
1.Measure:
●
Piston skirt diameter
Out of specification
→
Replace.
a
4.0 mm form the piston bottom edge
2.Calculate:
●
Piston-to cylinder-clearance
Refer to the “CYLINDER” section for cylinder
bore measurement.
Out of specification
→
Replace the piston
and piston rings as a set.
Piston skirt diameter:
69.977 ~ 69.996 mm
Oversize (2) 70.50 mm
Oversize (4) 71.00 mm
Piston-to-cylinder clearance =
Cylinder bore – Piston skirt diameter
Piston-to-cylinder clearance:
0.020 ~ 0.025 mm
<Limit: 0.05 mm>
3.Measure:
●
Piston pin bore diameter
Out of specification
→
Replace.
4.Measure:
●
Piston pin outside diameter
Out of specification
→
Replace.
5.Inspect:
●
Piston pin
Blue discoloration/groove
→
Clean or
replace.
Piston pin bore diameter:
16.002 ~ 16.013 mm
<Limit: 16.043 mm>
Piston pin outside diameter:
15.996 ~ 16.000 mm
<Limit 15.97 mm>