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CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
5. Remove:
• spark plug
6. Attach:
• adapter
• compression gauge
1
7. Measure:
• compression pressure
Above the maximum pressure:
Check the cylinder head, valve surfaces,
and piston crown for carbon deposits.
Below the minimum pressure:
Squirt a few drops of oil into the affected
cylinder and measure again.
Refer to the table below.
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a. Crank over the engine with the electric
starter (be sure the battery is fully charged)
with the throttle wide-open until the com-
pression reading on the gauge stabilizes.
Compression gauge
P/N. YU-33223, 90890-03081
Adapter
P/N. YU-33223-4, 90890-04082
Compression pressure
(with oil introduced into cylinder)
Reading
Diagnosis
Higher than
without oil
Worn or damaged pis-
tons
Same as with-
out oil
Defective ring(s), valves,
cylinder head gasket or
piston is possible.
Compression pressure
(at sea level)
Standard:
1,324 kPa
(13.24 kg/cm
2
, 188.31 psi)
Minimum:
1,150 kPa
(11.5 kg/cm
2
, 163.57 psi)
Maximum:
1,480 kPa
(14.8 kg/cm
2
, 210.50 psi)
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