Checking The Piston Diameter; Checking The Cylinder Bore - Yamaha F30B 2018 Service Manual

5. Remove:
• Piston pin clip "1"
• Piston pin "2"
• Connecting rod "3"
3

Checking the piston diameter

1. Measure:
• Piston outside diameter "a" (at the speci-
fied measuring point "b")
Below specification  Replace.
b
1
2
1
a
Piston
Diameter
64.950–64.965
2.5577 in)
Limit
64.910 mm (2.5555 in)
1st oversize diameter
65.200–65.215
2.5675 in)
2nd oversize diameter
65.450–65.465
2.5774 in)
Measuring point
5.0 mm (0.20 in)
above the bottom of the piston
skirt

Checking the cylinder bore

1. Measure:
• Cylinder bore (D1–D6) (at measuring
points "a", "b", and "c", and in directions "d"
(D1, D3, D5) and "e" (D2, D4, D6))
Above specification  Replace the cylin-
der block.
a
b
c
a. 10.0 mm (0.39 in)
b. 48.0 mm (1.89 in)
c. 85.0 mm (3.35 in)
d. Parallel to the crankshaft
e. At a right angle to the crankshaft
Cylinder
Bore
65.000–65.015
2.5596 in)
Limit
65.100 mm (2.5630 in)
7-51
Cylinder block
mm (2.5571–
mm (2.5669–
mm (2.5768–
D D
2 1
D D
4 3
D D
6 5
mm (2.5591–
d
e