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2·17 PERIODIC MAINTENANCE
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
maintenance records kept at your dealership should include compression readings for each main-
tenance service.
COMPRESSION PRESSURE SPECIFICATION
Standard
850 kPa
Approx. (8.5 k g /cm
2 )
120 psi
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 ful/y-charged condition.
Remove the parts concerned and test the compression pres-
sure in the following manner.
• Remove the spark plug.
• Fit the compression gauge in 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 start-
er, and record the maximum gauge reading as the com-
pression of that cylinder.
a
09915-64510: Compression gauge
0991 5-6331 0: Adaptor
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