Yamaha F4A - Crankcase Removal; Cylinder Inspection; Piston Inspection

E
CRANKCASE, CRANKSHAFT AND CAMSHAFT
POWR
D
D
1
2
D
D and D
1
2
D and D
3
4
D and D
5
6
70 mm (2.8 in)
40 mm (1.6 in)
10 mm (0.4 in)
1
2
a
d
SERVICE POINTS
Crankcase removal
1. Remove:
9Crankcase 1
9Cylinder body 2
NOTE:
9Position the crankcase up side down.
9Insert a flat-head screwdriver between the
tabs on both side of the crankcase and
cylinder body and pry open the two parts.
cC
Do not scratch the interface of the
crankcase and cylinder.
Piston inspection
1. Measure:
9Piston diameter
Out of specification ® Replace the
piston.
5-30
Standard Wear limit
Cylinder 59.00 ~ 59.02 mm
bore “D” (2.323 ~ 2.324 in)
—
Taper 0.08 mm
limit “T”
—
(0.003 in)
Out of 0.05 mm
round limit
—
(0.002 in)
D=Maximum Dia. (D
1
~D
6
)
T=(maximum D
1
or D
2
) ~ (minimum D
5
or
D
6
)
Distance
Piston diameter d
a
10 mm
58.950 ~ 58.965 mm
Standard
(0.39 in)
(2.3209 ~ 2.3215 in)
Cylinder inspection
1. Measure:
9Cylinder bore
Out of specification ® Rebore or
replace the cylinder.
NOTE:
Measure the cylinder bore in parallel and
at right angle to the crankshaft. Then, aver-
age the measurements.