Further Derbi adventures

Damn Derbis. So I have the spark all straightened out. Now it still doesn't run, but will pop a little if I spray ether into the spark plug hole. I think it has bad crankcase compression. When you turn over the engine, it doesn't make that sucking sound from the carb. I took off the amnifold and put my finger over the intake while i pedaled, and it seemed to draw air weakly. Can anyone with a Derbi confirm theirs is like this? Other than replacing the base gasket and splitting the engine to replace the case gasket, why can I do to fortify base compression?

Re: Further Derbi adventures

Hows the timing? You could test the engine leaks, but i dont know where you would get that tool.


Live to ride, Ride to work

Re: Further Derbi adventures

Does it leak psi if you put a compression tester on there?

Re: Further Derbi adventures

The timing is set correctly, I think. The top end compression, that is, compression after the exhaust port has closed, is good. I don't have a compression tester, but it feels good. i have seen a crankcase compression tester before, but it was a wierd special part on ebay, and i don't have one. I did put on a new base gasket the first time i took it apart. Could the thinner gasket be preventing a good seal? I can't detect any compression leaks. This is very frustrating.

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