2-22 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 should include compression readings for each maintenance service.
CONPRESSION PRESSURE SPECIFICATION
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. (!2-7)
• Install the compression gauge and adaptor in the spark plug
hole. Make sure that the connection is tight.
• Keep the throttle grip in the fully opened position.
• Press the starter button and crank the engine for a few sec-
onds.
• Record the maximum gauge reading as the cylinder compres-
sion.
# 09915-64510: Compression gauge set
09913-10750: Adaptor
Standard Limit
1 300 – 1 700 kPa
(13 – 17 kgf/cm
2
, 185 – 242 psi)
980 kPa
(9.8 kgf/cm
2
, 140 psi)
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