Mitsubishi 4G9 series Manual page 128

11A-12-6
4G9 ENGINE (E - W)
A
B
12 mm
Centre
Bottom
Piston O.D.
E
Mitsubishi Motors Corporation
-
Crankshaft, Cylinder Block, Flywheel and Drive Plate
(4) Using a cylinder gauge, measure the cylinder bore and
BORING CYLINDER
(1) Oversize pistons to be used should be determined on
Piston size identification
Size
Thrust
direction 0.50 mm O.S.
1.00 mm O.S.
(2) Measure outside diameter of piston to be used. Measure
(3) Based on the measured piston O.D., calculate the boring
(4) Bore all cylinders to the calculated boring finish dimension.
(5) Hone to the final finish dimension (Piston O.D. + clearance
(6) Check the clearance between piston and cylinder.
Nov. 1995
cylindricity. If worn badly, correct the cylinder to an
oversize and replace the piston and piston rings. Measure
at the points shown in illustration.
Standard value:
Cylinder inner diameter: 81.00 - 81.03 mm
Out-of-roundness and taper of cylinder bore: 0.01
mm or less
the basis of the largest bore cylinder.
NOTE
Size mark is stamped on the piston top.
it in thrust direction as shown.
finish dimension.
Boring finish dimension = Piston O.D. + (Clearance
between piston O.D. and cylinder) - 0.02 mm
(honing margin)
Caution
To prevent distortion that may result from temperature
rise during honing, bore cylinders, in the order of
No. 2, No. 4, No.1 and No. 3.
between piston O.D. and cylinder.)
Clearance between piston and cylinder:
0.02 - 0.04 mm
NOTE
When boring cylinders, finish all of four cylinders to the
same oversize. Do not bore only one cylinder to an
oversize.
PWEE9502-A
Identification mark
0.50
1.00
Revised