Piston Rings - Yamaha YB50 Service Manual

INSPECTION AND REPAIR
Standard
1st Clearance
2st Clearance
• If this is outside the specified value change
the piston and the set of rings.
Third step:
• Calculate the clearance of the piston to the
cylinder using the following formula:
Clearance of piston to cylinder =
Inner diameter of cylinder "C" –
Diameter of piston skirt "P"
• If this is outside the specified value, rectify
or change the cylinder and change the pis-
ton and set of rings.

PISTON RINGS

1. Measurement:
• Lateral clearance Outside specified value
a thickness gauge
Top ring
Second ring
2. Install:
• Piston rings on the cylinder
Press the ring and the piston crown
together.
4-13
Size of the piston P
39.952 ~ 39.997 mm
40.25 mm
40.50 mm
Cylinder-piston clearance
0.034 ~ 0.047 mm
Limit
0.1 mm
Change the piston and/or rings. Use
.
Standard
0.03~0.05 mm
0.03~0.05 mm
ENG
Limit
0.10 mm
0.10 mm