PERIODIC MAINTENANCE 2-27
COMPRESSION PRESSURE CHECK
The compression of a cylinder is a good indicator of its internal condition.
The decision to overhaul the cylinder is often based on the results of a compression test. Periodic mainte-
nance records kept at your dealership should include compression readings for each maintenance service.
COMPRESSION PRESSURE SPECIFICATION (Automatic de-comp. actuated)
Low compression pressure can indicate any of the following conditions:
* Worn-down piston or piston rings
* Piston rings stuck in grooves
* Poor seating of valves
* Ruptured or otherwise defective cylinder head gasket
Overhaul the engine in the following cases:
* Compression pressure in one of the cylinders is less than 1 100 kPa (11 kgf/cm
2
, 156 psi).
* Difference in compression pressure between two cylinders is more than 200 kPa (2 kgf/cm
2
, 28 psi).
* All compression pressure are below 1 100 kPa (11 kgf/cm
2
, 156 psi) even when they measure more than
1 300 kPa (13 kgf/cm
2
, 185 psi).
COMPRESSION TEST PROCEDURE
NOTE:
* Before testing the engine for compression pressure, make
sure that the cylinder head bolts are tightened to the specified
torque values and valves are properly adjusted.
* Have the engine warmed up by idling before testing.
* Be sure that the battery used is in fully-charged condition.
Remove the parts concerned and test the compression pressure
in the following manner.
• Remove all the spark plugs. (2-5 and -6)
• Fit the compression gauge in one of the plug holes, while tak-
ing care of the tight connection.
• Keep the throttle grip in full-open position.
• While cranking the engine a few seconds with the starter, and
record the maximum gauge reading as the compression of
that cylinder.
• Repeat this procedure with an other cylinder.
09915-64512: Compression gauge
09915-63210: Compression gauge adaptor
Standard Limit Difference
1 300 – 1 700 kPa
(13 – 17 kgf/cm
2
, 185 – 242 psi)
1 100 kPa
(11 kgf/cm
2
, 156 psi)
200 kPa
(2 kgf/cm
2
, 28 psi)
SAMPLE
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