Yamaha YW50AP, Service Manual

Page: 78 / 214

4-7
ENG
CYLINDER HEAD, CYLINDER AND PISTON
a
Measuring Point 20 mm(0.79 in)
PISTON PIN AND PISTON PIN BEARING
1. Inspect:
8
Piston pin
Blue discoloration/Groove
→
Replace,
then inspect lubrication system.
PISTON RINGS INSPECTION
1. Measure:
8
Side clearance
Out of specification
→
Replace piston
and/or rings.
Use a feeler gauge
1
Top ring 0.03 ~ 0.05 mm 0.1 mm
(0.0012 ~ 0.002 in) (0.0039 in)
2nd ring 0.03 ~ 0.05 mm 0.1 mm
(0.0012 ~ 0.002 in) (0.0039 in)
Standard Limit
2. Install:
8
Piston ring
Into the cylinder
Push the ring with the piston crown.
3. Measure:
8
End gap
Out of specification
→
Replace rings as
a set.
Use a feeler gauge
1
.
a
Top ring 0.15 ~ 0.35 mm 0.6 mm
(0.005 ~ 0.01 in) (0.02 in)
2nd ring 0.15 ~ 0.35 mm 0.6 mm
(0.005 ~ 0.01 in) (0.02 in)
Standard Limit