6-15
Chapter 6 INSPECTION AND REPAIR OF BASIC ENGINE
4. Piston and Connecting Rod - Inspect and Repair
4.1 Piston - Inspect Visually
Check the combustion surface, piston pin bore, ring groove,
sliding surface and bottom surface of piston. If any defect
are found, replace the piston with a new one.
Piston - Inspect Visually
4.2 Piston Weight
Check the piston weight on the top face of piston.
When replacing pistons, be sure that the weight difference
per engine is within permissible range.
Piston weight punch mark
4.3 Piston Outside Diameter - Measure
Measure the piston outside diameter of piston skirt at right
angle to piston pin.If the value exceeds the limit, replace the
piston with a new one.
Piston Outside Diameter - Measure
4.4 Piston Ring Groove - Inspect
(1) Remove all deposits such as carbon from each ring
groove.
(2) Visually check each ring groove for wear or damage. If
faulty, replace the piston with a new one.Inspect the
ring insert of No. 1 compression ring groove by dye
penetration test for cracks and separation.
Piston Ring Groove - Inspect
Item Part No. ID stamp
Com-
pres-
sion
ratio
Standard value
Piston
weight
differ-
ence
32517-91101 91101 14
Within ±15 g
[0.53 oz]
32617-00701 00701 15
32517-91201 91201 14
Within 20 g
[0.71 oz]
32617-00600 00600 15
(
(
Piston weight mark
Part number (last 5 digits)
Engine front
direction mark
[F]
Item
Nominal
value
Standard
value
Limit value
Piston outside
diameter
ø150 mm
[5.9 in.]
149.71 to
149.75 mm
[5.8941 to
5.8957 in.]
149.68 mm
[5.8929 in.]
30 mm
[1.18 in.]
Measurement
point
Remove carbon deposits from piston and inspect the
entire circumference of piston.
Ring carrier
No.1 compression ring
groove
No.2 compression ring
groove
Oil ring groove
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