2-24 PERIODIC MAINTENANCE
COMPRESSION PRESSURE CHECK
The compression pressure reading 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 shoud include compression readings for each maintenance service.
$ Compression pressure:
Standard: 1 000 kPa (10.0 kgf/cm², 142 psi)
Service Limit: 800 kPa (8.0 kgf/cm², 114 psi)
(Automatic decompression actuated)
Low compression pressure can indicate any of the following conditions:
* Excessively worn cylinder walls
* Worn piston or piston rings
* Piston rings stuck in grooves
* Poor valve seating
* Ruptured or otherwise defective cylinder head gasket
NOTE:
When the compression pressure goes below specification, check the engine for conditions listed above.
COMPRESSION TEST PROCEDURE
NOTE:
* Before testing the engine for compression pressure, make
sure that the cylinder head nuts are tightened to the specified
torque values and the valves are properly adjusted.
* Warm up the engine before testing.
* Make sure that the battery is fully charged.
Remove the related parts and test the compression pressure in
the following manner.
• Remove the spark plug. ("2-6)
• Install the compression gauge and adaptor in the spark plug
hole. Make sure that the connection is tight.
• Keep the throttle lever in the fully open position.
• Press the starter button and crank the engine for a few sec-
onds. Record the maximum gauge reading as the cylinder
compression.
% 09915-64512: Compression gauge set
09915-63310: Adaptor
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