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CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
6. Measure:
• compression pressure
Out of specification → Refer to steps (c)
and (d).
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a. Set the main switch to “ON” and the engine
stop switch to “”.
b. With the throttle wide open, crank the
engine until the reading on the compression
gauge stabilizes.
WARNING
_
To prevent sparking, ground the spark plug
lead before cranking the engine.
c. If the compression pressure is above the
maximum specification, check the cylinder
head, valve surfaces, and piston crown for
carbon deposits.
Carbon deposits → Eliminate.
d. If the compression pressure is below the
minimum specification, pour a teaspoonful
of engine oil into the spark plug bore and
measure it again.
Refer to the following table.
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Compression pressure (at sea
level)
Minimum
600 kPa (6.0 kg/cm
2
, 85.3 psi)
Standard
650 kPa (6.5 kg/cm
2
, 92.4 psi)
Maximum
700 kPa (7.0 kg/cm
2
, 99.6 psi)
Compression pressure
(with oil applied into the cylinder)
Reading Diagnosis
Higher than with-
out oil
Piston ring(s) worn
or damaged
→
Repair.
Same as without
oil
Piston, valves, cyl-
inder head gasket
or piston possibly
defective
→
Repair.