rings and rotate them in their respective grooves to be sure
that they move smoothly.
Carbon in groove is liable to cause the piston ring to get stuck
in the groove.and this condition will lead to reduced engine power
output.
A piston whose sliding surface is badly grooved or scuffed due to
overheating must be replaced.
Shallow grooves or minor scuff can be removed by grinding with
emery paper of about#400.
PISTON PIN BORE
Using a caliper gauge.measure the piston pin bore inside
diameter.if reading is exceeded the following service limit.
replace it with a new one.
Service limit
10.030mm
PISTON PIN O.D.
Using a micrometer.measuer the piston pin outside diameter
at three positions.
Service limit
9.980mm
PISTON RINGS
Check each ring for end gap.reading the gap with a thickness
gauge shown in Fig.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 measured with the ring fitted
squarely into the cylinder bore and held at the least worn part
near the cylinder bottom.as shown in Fig.
Service limit
0.75mm
As the piston ring wears.its end gap increases reducing engine
power output because of the resultant blowby through the enlarged
gap.here lies the importance of using piston rings with end gaps
within the limit.
Measure the piston ring free end gap to check the spring tension.
1
st
3.2mm
Service limit
2nd 3.3mm
Fix the piston ring in the piston ring groove. Measure the ring
side clearance with the thickness gauge while matching the sliding
surfaces of piston and ring.
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