Operation Manual

CYLINDER AND PISTONS
5-31
b. If out of specification, replace the cylinder,
piston and piston rings as a set.
c. Measure piston skirt diameter “a” with the
micrometer.
d. If out of specification, replace the piston
and piston rings as a set.
e. Calculate the piston-to-cylinder clearance
with the following formula.
f. If out of specification, replace the cylinder,
piston and piston rings as a set.
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EAS24430
CHECKING THE PISTON RINGS
1. Measure:
• Piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
TIP
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the
piston ring grooves and piston rings.
2. Install:
•Piston ring
(into the cylinder)
TIP
Level the piston ring into the cylinder with the
piston crown.
Bore = maximum of D
1
–D
2
Taper limit = maximum of D
1
or D
2
- maxi-
mum of D
5
or D
6
Out of round limit = maximum of D
1
, D
3
or D
5
- minimum of D
2
, D
4
or D
6
b. 9.0 mm (0.35 in) from the bottom edge of
the piston
Piston
Diameter
67.975–67.990 mm (2.6762–
2.6768 in)
• Piston-to-cylinder clearance =
Cylinder bore -
Piston skirt diameter
Piston-to-cylinder clearance
0.010–0.035 mm (0.0004–
0.0014 in)
Limit
0.15 mm (0.0059 in)
Piston ring
Top ring
Ring side clearance
0.030–0.065 mm (0.0012–
0.0026 in)
Limit
0.100 mm (0.0039 in)
2nd ring
Ring side clearance
0.020–0.055 mm (0.0008–
0.0022 in)
Limit
0.100 mm (0.0039 in)