Nissan 5 HP 4-Stroke with low compression

Picked up a 2002 Nissan 5 HP 4-Stroke (NSF5A2) and trying to resurrect it. It has good spark but low compression (25 PSI cold). I put some oil in the cylinder and the compression increased to 50 PSI - still way low. It will pop a few times after I inject the oil into the cylinder. Checked the valves and they had the proper clearance. Pulled the lower unit and injected air into the water tube and no air came out through the spark plug hole. Thus, I think the head gasket is OK? I think the problem is worn rings? Drained the oil and there was no water in it. Lots of black soot on the driveshaft. I was going to disassemble the power head (if I don't break off too many bolts) and look and the cylinder walls and if OK replace the rings. It is a salt water motor so it may have to be turned into a parts motor which I hate to do . Anything I missed here?? Suggestions?? Thanks .................

Is there an automatic compression release on it ?

It has a decompressor, so that's normal. Check the carburetor.

Pulled the carb off, cleaned it and seemed to be fine. Please explain how the carb can cause low compression? Thanks

Wrong.------Decompression feature would be on the camshaft.

The carb didn't cause low compression. The carb caused it to not run well. The compression is likely perfect.

Well, decided to tear it down and see what was the cause of the low compression. The carb had nothing to do with it. Tore everything apart and was surprised how easy it came apart for a saltwater motor. No broken bolts and did not have to heat any to get them out. The problem was the cylinder walls. The cylinder was pitted pretty badly. I think that is what caused the rings to wear and the low compression. I also think it was a flaw in the manufacturing. Bad steel cylinder. Quality control lacking here.
Well, putting the parts on EBay for sale.