Generic XOR 50 ccm, Руководство по обслуживанию

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37
Unit
：
mm
Piston pin bore
Use a caliper gauge to measure the piston pin bore inside diameter,. If reading
exceeds the following service limit, replace it with a new one.
(Dial caliper)
Limit service: 12.30mm(0.4736in)
Piston pin outside diameter
：
Use a micrometer to measure the piston outside
diameter at three positions.
(Micrometer
（
0-25mm
）
)
service limit
：
11.980mm(0.4717in)
Piston rings
Check each ring for end gap, reading the gap with a
thickness gauge shown in the illustration. If the end gap
is found to exceed the limit, indicated below, replace it
with a new one.
The end gap of each ring is to be measued with the ring
fitted squarely into the cylidner bore and held at the
least worn part near the cylidner bottom, as shown in
the illustration.
Service limit
：
0.75mm(0.030in)
As the piston ring wears, its end gap increases reducing
reducing engine power output becaust of the resultant
blow by through the enlarged gap. Here lies the
importance of using piston rings with end gaps with the
limit. Measure the piston ring free end gap to check the
spring tension.
service limit
：
3.6mm(0.14in)
Fix the piston ring in the piston ring groove, measure the ring side clearance with the
thicknes gauge while matching the sliding surface of piston and ring.
Standard service
limit
Cylinde
r
40.005-40.0
20
40.075
Piston 39.94-39.955 39.885
Cylinder to
piston
0.06-0.07 0.120