Reply To: Another new guy question

[Don]

I am assuming you checked the shear pin on the 3hp with the prop that doesn’t spin with the flywheel….If that is OK, then I will sadly agree with Frank, the crank/driveshaft splines are probably shot, which is the end of the road for this engine.
And yes, 50PSI is pretty low, but not shocking for this little engine. You have the head off now, is the head gasket OK? These engines have such small combustion chambers, compression gage readings are often inaccurate. Compression readings are usually between 70-90PSI for these little engines. If it was mine, I would not tear it apart. I would use some fine emery on the cylinder walls and give it the 50cent hone job. Resurface the cylinder head to make sure it is flat, then reassemble with a new head gasket. I’m betting it will run and the compression will come up a bit…I am assuming there is not aluminum scuffing on the cylinder walls or major scoring.
You could always pull off the exhaust cover (if it is a fresh water motor and the screws aren’t rusted/stuck), this will give you a better look inside to check the pistons for stuck/rusted rings, or scuffs and scoring on the pistons….