My morini m01 engine was running. It would run for about 15 minutes and then stall. I checked the compression and it was around 80 to 90 psi. I ordered a piston and rings from a Garrelli that matched the measurements of my cylinder. The bike ran okay for a few miles then died. Compression is now minimal and the top of the new piston is black with carbon. What did I do wrong and how do I fix it?

Re: pistons?

things besides worn rings can cause low compression.. loose head bolts, a cracked or warped head.. the rings could be stuck in their grooves .. a leaking decompression valve, etc.

the question is what caused the engine to stall.. Find that and you'll probably be close to finding the primary problem.

How does it run now .. anything weird besides the carboned piston?

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