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31
IV. ENGINE
I"--
Inspection
lo Measure the inside diameter of each cylinder.
Measure the bare at the top, middIe and bottom with an
accurate cylinder gauge placed at righi angle (X) and
parallel (Y) to the center line of the crankshafto
Standard value: 70.0-70.01mm (2.7559-2.7564-ino)
Service limit:
?O.llmm (2.76-m.)
If the wear is so great that the service limits afe exceeded,
the cylinders should be rebored and oversize pistons and
piston rings installed. The following four oversize pistons
and piston rings afe available as service parts:
Fig. 4-32
Measuring cylinder bore
Fig. 4-33
Measuring piston ring end gap
2. Measure the outside diameter of the piston at its skirt.
Standard value: 69.9S-69.97mm (2.7S4-2.7SS-in.)
Service limit:
69.87mm (2.7S1-in.)
3. Measure the inside diameter of the piston pin hole in the
piston.
Standard value: 17.002-17 .OO8mm (O.6693-,-O.6696-in.)
Service limit:
17.1mm (0.6732-in.)
4. Measure the outside diameter of the piston pino
Standard value: 16.994-17.0Omm (O.6690-0.6693-in.)
Service limit:
16.9Smm (O.6673-in.)
50 Check the clearance between the piston ring and ring
groove.
S tandard value
Service limit
Top:
0.O40-0.07Omm
O.ISmm (O.OO6-in.)
(0.OOI6-000028-in.)
Second: 0.020-0.04Smm
O.ISmm (O.006-in.)
(O.OOO8-0.0018-in.)
6. Check the piston ring end gap using a feeler gauge.
Standard value
Service limit
Top:
O.3-0.Smm
O.8mm (O.031-in.)
(O.OI3-0.03-in:)
Second: O.3-0.S~
O.8mm (O.031-in.)
(O.OI2-0.03-in.)
Oil:
O.2-0.4mm
0.8mm (O.O31-in.)
(O.OO8-0.016-in.)
Assembly
Piston rings
l. To install the oil ring, first piace the spacer and then the
rails in position. The spacer and rail gaps must be staggered
20-30mm (O8-1.2-in.).
2. lnstall the second and top rings in this arder in the piston
with their markings facing upward.
NOTES:
a. Do not mix the top and second rings.
b. After installing alI rings in the piston, hand-rotate them
and check to be sure they move smoothly without any
sign of binding.
Fig. 4-34
(I) Top ring
(4) Spacer
(2) Second ring (5) Piston ring marking
(3) Rail
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