Piston And Pistonrings Removal; Cylinder Inspection - Yamaha YP250 Service Manual

CYLINDER AND PISTON
YP******
PISTON AND PISTON RINGS REMOVAL
1. Remove:
S Piston pin circlip 1
S Piston pin 2
S Piston 3
NOTE:
Before removing the piston pin circlip, cover the
crankcase opening with a clean towel or rag to
prevent the circlip from falling into the crank-
case cavity.
2. Remove:
S Top ring
S 2nd ring
S Oil ring
NOTE:
When removing the piston ring, open the end
gap of the ring by fingers, and push up the other
side of the ring.
YP402100

CYLINDER INSPECTION

1. Measure:
S Cylinder bore
Out of specification ! Rebore or replace
NOTE:
D Measure the cylinder bore with a cylinder
bore gauge.
D Measure the cylinder bore in parallel to and at
right angles to the crankshaft. Then, find the
average of the measurements.
Cylinder bore:
69.000 X 69.005 mm
<Limit: 69.1 mm>
<Defferance limit between A, B
and C: 0.03 mm>
2. Measure:
S Warpage
Out of specification ! Replace.
Cylinder warpage limit:
0.03 mm
4-22
ENG