Cagiva Navigator, Workshop Manual, Page: 35 / 407

B.27
MAINTENANCE
COMPRESSION TEST
The compression of a cylinder is an optimum indicator of the internal condition of the engine.
The decision to overhaul the engine is often the result of a compression test. Amongst the periodical maintenance
data to be found at the dealer are also the compression measurements for each maintenance operation.
COMPRESSION SPECIFICATION (automatic decompression activated)
Standard Limit Difference
1300-1700 kPa 1100 kPa 200kPa
( 13-17 kg/cm 2 ) ( 11 kg/cm 2 ) ( 2 kg/cm 2 )
Low compression could indicate one of the following conditions:
* Worn piston or piston rings
* Piston rings seized in the grooves
* Poor valve closure
* Head gasket broken or defective
Overhaul the engine in the following cases:
* The compression of one of the cylinders is less than 1100 kPa (11 kg/cm
2 ).
* The difference between the compression of the two cylinders is more than 200 kPa.
* All values of the compression are less than 1300 kPa (13 kg/cm
2
) even if they are more than 1100 kPa (11 kg/cm
2
).
COMPRESSION TEST PROCEDURE
* Before verifying the engine compression, check that the cylinder head bolts are tightened to the correct torque
and that the valves are adjusted correctly.
* Heat up the engine before proceeding with the test.
* Check that the battery is fully charged.
• Carry out the compression test as follows:
• Remove the seat and the plastic underneath the seat.
• Remove both spark plugs (see page B-7.)
• Screw in the compression meter in one of the spark plug holes
making sure that it is correctly tightened.
• Keep the accelerator handgrip in the fully open position.
• Turn over the engine with the electric starter motor for several
seconds and note the maximum reading of the compression me-
ter. This is the compression of that cylinder.
• Repeat the procedure for the other cylinder.
Special tool: 800096660: Compression meter
800096652: Compression sensor adaptor