PERIODIC MAINTENANCE 2-21
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 re-
sults of a compression test. Periodic maintenance records kept
at your dealership should include compression readings for each
maintenance service.
COMPRESSION PRESSURE SPECIFICATION
Standard
1 100 – 1 500 kPa
(at about 600 rpm)
(11 – 15 kgf/cm
2
)
Low compression pressure can indicate any of the
following conditions:
* Excessively worn cylinder wall
* Worn-down piston or piston rings
* Piston rings stuck in grooves
* Poor seating of valves
* Ruptured or otherwise defective cylinder head gasket
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 pres-
sure in the following manner.
• Remove all the spark plugs.
• Fit the compression gauge in one of the plug hole, while taking
care that the connection tight.
• 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.
% 09915-64510: Compression gauge
09915-63310: Adaptor
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