Checking The Piston Diameter; Checking The Cylinder Bore - Yamaha F100C Service Manual

NOTE:
Do not remove the ignition timing pointer
from the crankcase.
3. Remove the connecting rod bolts and the
connecting rod caps.
NOTE:
• Be sure to keep the bearings in the order as
they were removed, and to note the bearing
color of the bearing.
• After removing the connecting rods, mark
each cylinder for identification.
4. Remove the crankshaft, oil seals, and the
piston assemblies.

Checking the piston diameter

1. Measure the piston outside diameter at
the specified measuring point. Replace if
out of specification.
Piston diameter a:
78.93–78.94 mm
(3.1075–3.1078 in)
Measuring point b:
13 mm (0.5 in) up from the bottom
of the piston skirt
Oversize piston diameter:
79.18–79.19 mm
(3.1174–3.1177 in)
Oversize 1: +0.25 mm (0.0098 in)
60C5D11

Checking the cylinder bore

1. Measure the cylinder bore (D
measuring points a, b, and c, and in
direction d (D
, D
1 3
to the crankshaft, and direction e (D
D , D ), which is at a right angle to the
4 6
crankshaft.
D
2
D
4
D
6
a 20 mm (0.8 in)
b 70 mm (2.8 in)
c 120 mm (4.7 in)
Cylinder bore (D
79.00–79.02 mm
(3.1103–3.1110 in)
2. Calculate the taper limit. Replace or
rebore the cylinder body if out of specifi-
cation.
Taper limit:
(direction d)
D –D
1 5
(direction e)
D –D
2 6
0.08 mm (0.0031 in)
3. Calculate the out-of-round limit. Replace
or rebore the cylinder body if out of spec-
ification.
Out-of-round limit:
(measuring point a)
D –D
2 1
(measuring point c)
D –D
6 5
0.08 mm (0.0031 in)
Cylinder body
–D ) at
1 6
, D ), which is parallel
5
,
2
D
1
D
3
D
5
S60C5830
–D ):
1 6
5-40
1
2
3
4
5
6
7
8
9