Service Manual

23
Piston – Inspect/Replace
Remove the connecting rod bolts (1) and the rod
cap (2). Push the connecting rod (3) and piston
(6) out of the block. Remove any carbon
deposits. Inspect the cylinder bore. If the
cylinder wall is damaged, replace the crankcase.
Use a ring puller to remove piston rings (7), (8),
and (9). Inspect the rings. Replace if damaged
or worn. Remove the piston pin clips (4) and
piston pin (5). Measure the piston pin bore
inside diameter. Measure the piston pin outside
diameter. If the difference is 0.08mm or more,
replace the worn part. Inspect the top of the
piston (6) for burns and cracks. Inspect the
piston ring grooves for damage. If any damage
or wear is found, replace the piston. Measure
the piston skirt and compare the measurement
to the following chart.
Model: Normal: Minimum:
RP12000E 77.98mm 77.86mm
If the measurement is less than the minimum
value shown in the chart, replace the piston. Set
the piston into the cylinder and measure the
clearance between the piston and the cylinder
wall by inserting a feeler gauge. If the clearance
is 0.12mm or more, replace the piston.
Measure the ring clearance, as shown. Normal
clearance is between 0.03 – 0.07mm. If the
clearance is 0.135mm or more, replace the
piston. Install the oil ring onto the piston and
insert the piston into the cylinder. Measure the
end gap of the oil ring. Normal values are shown
in the chart below. If the end gap is 1.0mm or
more, replace the oil ring. If the end gap is less
than 0.20mm, use a fine file to increase the gap.
Take care not to leave any sharp edges.
Ring Gap
Model:
Top Ring
/
Second Ring:
Oil Ring:
RP12000E 0.20 – 0.35mm 0.20 – 0.70mm
Install the second ring onto the piston and insert
the piston into the cylinder. Measure the end
gap of the ring. Normal values are shown in the
chart above. If the end gap is 1.0mm or more,
replace the oil ring. If the end gap is less than
0.20mm, use a fine file to increase the gap.
Take care not to leave any sharp edges. Repeat
this procedure for the top ring.
Connecting Rod:
Check the connecting rod. If the connecting rod
is bent or cracked, replace the connecting rod.
Measure the pin end inside diameter. Install the
rod cap and measure the inside diameter of the
crank end of the connecting rod. Normal
diameters and service limits are shown in the
chart below. If the diameter is at or exceeds the
maximum value, replace the connecting rod.
Connecting Rod Ends Inside Diameters
Pin End:
Model: Normal: Maximum:
RP12000E 17.005mm 17.046mm
Crank End:
RP12000E 40.01mm 40.06mm
Installation:
The piston head has a triangular mark to aid in
assembly.
2
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3
4
5
6
7
8
9
4
1
2