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3 HP two-stroke question--PLEASE HELP!

whitejw1967

New member
I am trying to find out what the compression should be for a Yamaha 2-stroke (3hp) and to get ideas. My engine starts and runs well, but it is not producing enough power (it tops out at roughly 50% of thrust). My friend's 2hp 2 stroke Yamaha produces 100% more power than mine. The throttle runs best at its average setting; adding more power simply puts unused fuel mixture in the exhaust.

We are having trouble diagnosing the problem. We think we've narrowed it down to carb jet issues or compression. Our repeated attempts to determine the compression came out consistently at about 150 PSI.

John
 
that is excellent compression.------The problem lies somewhere else.-----------------Check reed valves.-------Inspect for plugged / flooding carburetor.
 
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