Compression Pressure Check - Suzuki GSX-R750 Service Manual

2-30 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.
COMPRESSION PRESSURE SPECIFICATION
Standard
1 100 – 1 500 kPa
2
11 – 15 kgf/cm
156 – 213 psi
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
Overhaul the engine in the following cases:
* Compression pressure in one of the cylinders is less than 900
kPa (9 kg/cm 2 , 128 psi).
* The difference in compression pressure between any two cyl-
inders is more than 200 kPa (2 kgf/cm
* All compression pressure readings are below 1 100 kPa (11
2
kgf/cm , 156 psi) even when they measure more than 900 kPa
2
(9 kgf/cm , 128 psi).
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.
* Have the engine warmed up before testing.
* Make sure that the battery is fully-charged.
Remove the related parts and test the compression pressure in
the following manner.
• Lift and support the fuel tank. ( 4-51)
• Remove all the spark plugs. ( 2-5)
• 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 com-
pression.
• Repeat this procedure with the other cylinders.
[ [
[ [ 09915-64510: Compression gauge set [
09913-10750: Adaptor
Limit Difference
900 kPa 200kPa
2
9 kgf/cm 2 kgf/cm
128 psi 28 psi
2
, 28 psi).
2