Checking The Piston Ring Grooves; Checking The Piston Ring Side Clearance; Checking The Piston Pin Boss Bore; Checking The Piston Pin - Yamaha FT50C Service Manual

Checking the piston ring grooves

1. Measure the piston
Replace the piston if out of specification.
Piston ring groove:
Top ring a:
1.23–1.25 mm (0.048–0.049 in)
Second ring b:
1.52–1.54 mm (0.060–0.061 in)
Oil ring c:
2.51–2.53 mm (0.099–0.100 in)
Checking the piston ring side
clearance
1. Measure the piston ring side clearance.
Replace the piston and piston rings as a
set if out of specification.
62Y5A11
ring grooves.
Piston ring side clearance:
Top ring a:
0.04–0.08 mm (0.002–0.003 in)
Second ring b:
0.03–0.07 mm (0.001–0.003 in)
Oil ring c:
0.05–0.19 mm (0.002–0.007 in)

Checking the piston pin boss bore

1. Measure the piston pin boss bore.
Replace the piston if out of specification.
Piston pin boss bore:
15.974–15.985 mm
(0.6289–0.6293 in)

Checking the piston pin

1. Measure the piston
Replace if out of specification.
Piston pin diameter:
15.965–15.970 mm
(0.6285–0.6287 in)
Cylinder body
pin diameter.
5-40
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