PERIODIC MAINTENANCE 2-29
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 800 kPa (8 kgf/cm², 114 psi).
* Difference in compression pressure between two cylinders is more than 200 kPa (2 kgf/cm², 28 psi).
* All compression pressure are below 1 000 kPa (10 kgf/cm², 142 psi) even when they measure more than
800 kPa (8 kgf/cm², 114 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 the radiator. (!5-4)
• Remove all the spark plugs. (!2-5)
• 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.
$ 09915-64510: Compression gauge
09913-10750: Adaptor
Standard Limit Difference
1 000 – 1 400 kPa
10 – 14 kgf/cm
2
142 – 199 psi
( )
800 kPa
8 kgf/cm
2
114 psi
( )
200 kPa
2 kgf/cm
2
28 psi
( )
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