2-30 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 mainte-
nance records kept at your dealership should include compression readings for each maintenance service.
COMPRESSION PRESSURE SPECIFICATION
Low compression pressure can indicate any of the following conditions:
* Excessively worn cylinder walls
* 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 1 200 kPa (12 kgf/cm², 171 psi).
* Difference in compression pressure between two cylinders is more than 200 kPa (2 kgf/cm², 28 psi).
* All compression pressure are below 1 500 kPa (15 kgf/cm², 213 psi) even when they measure more than
1 200 kPa (12 kgf/cm², 171 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.
• Support the motorcycle with the center stand.
• Move the radiator. (2-6)
• Remove all the spark plugs. (2-6)
• 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.
[ 09915-64512: Compression gauge
09915-63311: Compression gauge attachment
09915-74521: Gauge hose
Standard Limit Difference
( )
1 500 – 1 900 kPa
15 – 19 kgf/cm
2
213 – 270 psi
1 200 kPa
12 kgf/cm
2
171 psi
( )
200 kPa
2 kgf/cm
2
28 psi
( )
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