Service Manual

Piston
1. Measure the outside diameter
of the piston.
The piston should measure 63.960 63.975
mm (2.5181 2.5187 in.).
If the piston
measures less than 63.915 mm (2.5163 in.)
replace it. See Fig. 4-37.
Piston Diameter
63.960-63.975 mm (2.5181-2.5187)
14 mm (0.55 in)
Figure 4-37
2. Measure the piston pin diameter. The pin
should measure 14.995 15.00 mm (5904
5906 in.) See Fig. 4-38.
Piston Pin Diameter
14.995-15.00 mm (S904-.5906 in.)
Figure 4-38
3. The clearance between the piston pin and
connecting rod bearing should be .006
.019 mm (.0002 ,0007 in.). The wear limit
is
.05 mm (.002 in.). Both the connecting rod
and piston pin must be replaced if the wear
limit is exceeded.
Cylinder
1. Diameter of the cylinder is 64 mm
(2.52 in.).
Cylinder bore condition is determined by
establishing the total cylinder bore wear.
2. Take a total of 6 cylinder measurements as
shown in Fig. 4-39. Take two measurements
each at point
A, B. C.
c
Cylinder Bore
Measurement
Figure 4-39
The amount of wear is the difference be-
tween the largest and smallest measure-
ments.
3. The wear limit is .1 mm (.0039 in.).
Piston Rings
1. Measure the piston ring clearance in the
piston ring groove. See Fig. 4-40.
Clearance .03-.07 mm (.0012-.0028 in.)
Wear Limit .1 mm (.0039 in.)
Piston Ring Clearance in Groove
-03-.07 mm (.0012-.0028 in.)
Figure 4-40
2. Measure the piston ring end gap where
cylinder wear is at a minimum. This will be
about 3 mm (1/8 in.) from the upper edge of
the cylinder. The end gap measured with a
feeler gauge is .20-.40 mm (.0079-,0158 in.).
The limit is .7 mm (.027 in.).
Valves
1. Measure the valve stem diameter. See Fig.
4-41.
Intake Valve 5.460-5.475 mm
(.2150-.2156 in.)
Exhaust Valve- 5.440-5.455 mm
(.2142-,2148 in.)
2. Use a small bore gauge and a micrometer to
measure the valve guide
I.D.
Intake & Exhaust- 5.500-5.512 mm
(.2165-,2170 in.)
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