69 Merc 100 with one cylinder down in compression

[69Alumacraft]

I have a 1969 Mercury 1000 (100 hp) that has the #1 cylinder with compression around 90 psi and the other 5 are around 120 psi . We poured a little 30 wt. oil into the cylinder and that brought it up to about 115 psi.

The boat hasn't been run in a year when I had problems with it bogging down and dying on me (1969 Merc 100 not running under load). Could this just be a problem with not having run it in awhile and the top cylinder didn't have enough/any oil? Would we get more consistent numbers if we ran it for awhile on the hose and then checked?

I know nothing about 2 strokes, so I'm sure where to proceed from here. I live in the middle of the Mojave and there aren't any marine mechanics in the area. Would this be something that a motorcycle mechanic could work on (since, I assume, a 2 stroke is a 2 stroke is a 2 stroke)?

Any guesses on what it would cost to fix?

 

[69Alumacraft]

UPDATE: 69 Merc 100 with one cylinder down in compression

UPDATE: 69 Merc 100 with one cylinder down in compression

I ran the motor for about 10 minutes on the hose and now the #1 cylinder is at 105psi and the others are still at 120psi.

Is this close enough?

 

[Aqualift]

Re: 69 Merc 100 with one cylinder down in compression

Well, it's outside the usual range of 5lbs +/-. Some allow up to 10lbs difference. A sticky ring, possibly. But it could be a sign of an issue with that cylinder. I would probably investigate further to prevent more serious issues or damage.