JAC J2 - Page 79

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
Maintenance Manual for J2 Sedan
Mechanical Part of Engine
78
Attention:
■
Be
careful to
prevent gasket
materials
from falling
into the
engine oil
or
coolant.
Measure planeness of cylinder body in different
directions at six positions using ruler and feeler gauge.
Standard values: below 0.05mm
Limits: below 0.1mm
If the limit is exceeded, replace cylinder body.
⑥
 Cylindricality of Cylinder
Measure the cylinder degree at 6 different points per cylinder by using micrometer.
Standard values:
For cylinder bore: 75.0mm
For cylindricality: below 0.07mm
⑦

Diameter
of
Piston
Skirt
Use outside micrometer to check whether the
piston skirt is distorted.
Standard values:74.973mm
⑧
 Clearance between Piston and Cylinder
Bore
Calculate per the actual measurement of piston skirt and cylinder bore.
(Gap)
＝

(inner diamet
er
of
cylinder)
－

(diamet
er of
piston ski
rt)
Standard value: 0.02-0.04mm
If the calculated value exceeds the limit, replace piston and piston ring assembly.
⑨

Boring
Cylinder
a.
The piston
with
extended size
to be
used
should be
determined in
accordance with
the
cylinder
which has the highest bore.
Pistons of the following extended sizes, i.e. 0.25mm, 0.50mm, 0.75mm and 1.00mm, are applicable.
b.
Measure
the
diameter
of
piston
to
be
used.
After boring cylinder, clearance between piston and cylinder bore must be within standard range. The
Fig.1.1.063
Fig.1.1.064
Feeler
G
a
u e

Ruler

Dial Indicator
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