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sir,what should i do with my motorcycle is suffering of lost compression...kawasaki gpz400r model.1989...

Hi Razel,

You will have to determine where the compression is being lost.

It might be that the valves do not have enough clearance and will
need to be adjusted by changing the shims.

You can try a small bit of oil in the cylinders to see if that
brings the compression up.
If oil helps the compression alot then you may need to rebuild
the top end of the engine. This would be the pistons, rings and
cylinders repaired and checking the valves for leakage.

The valve clearance can be checked by removing the top cover
on the engine. Put the cylinder you are checking on it's pressure
or compression stroke. Check the clearance under the cam lobes
and above the rocker arms.

Valve clearance shoud be minimum of 0.16 mm or  .006" inches and maximum of 0.18 mm
or about .007" inches.

You may need to take the engine apart to correct the problem.
Parts may be hard to find for that year of bike but
sometimes parts can be substituted from similar models
like the larger 550 or 600 cc.

I would suggest first looking at what parts are available around the internet
for that year and model of Kawasaki.


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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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