Yamaha SX150C Service Manual page 136

POWR
CYLINDER BODY ASSEMBLY
5450
5460
5470
CALCULATING THE PISTON-TO-
CYLINDER CLEARANCE
Calculate:
• Piston-to-cylinder clearance a
Out of specification → Replace the pis-
ton and piston rings, the cylinder or
both.
Piston-to-
cylinder =
clearance
Piston-to-cylinder clearance
Cylinder #1
0.150 - 0.156 mm
(0.0059 - 0.0061 in)
Cylinders #2 - #6
0.100 - 0.106 mm
(0.0039 - 0.0042 in)
INSPECTING THE PISTON PINS AND
SMALL-END BEARINGS
1. Inspect:
• Piston pin
• Small-end bearing
Heat discoloration → Replace.
Damage/scratches → Replace.
2. Measure:
• Piston pin diameter
(with a micrometer)
Out of specification → Replace.
Piston pin diameter
23.065 - 23.070 mm
(0.9081 - 0.9083 in)
3. Measure:
• Piston pin boss diameter
(with a micrometer)
Out of specification → Replace.
Piston pin boss diameter
23.074 - 23.085 mm
(0.9084 - 0.9089 in)
5-49
Cylinder
Piston
bore –
diameter
diameter
E
5
5