One cylinder has low reading...

[ocuyler]

I know this is basic stuff, so please forgive my ignorance on outboard motors.

#1 cylinder of 4 cylinders on my 1967 Mercury 500 50 HP short shaft reads 25 PSI, where the other three are 125 PSI each.

Before dropping it off for service, I ran this motor through it's paces while still attached to it's host, a 1963 Boston Whaler 13 Sport. With fresh fuel, she started right up, shifted smoothly in both directions and seemed to have reasonable, but not over whelming power. It sounded fine at all speeds, including WOT. I was actually impressed with the lack of 2 stroke smoke.

What is the significance of this cylinder reading? Will it run reliably like this for awhile? Can anything be done short of a teardown to improve the compresion in #1 cylinder?

As much as I'd love to hang a 2005 e-tec on there at $4,000, that's NOT going to happen to this boat. Your comments will be appreciated.