Low compression in cylinder with no spark

[AEROCOOK]

As mentioned in a previous post, my 1988 Johnson 110 had no spark in one cylinder and I had run the boat for about 3 hours in this condition.
I now have the spark condition resolved but the compression in that cylinder is lower than the other 3, it is reading around 104 while the other 3 at at 116 to 118.
My question is whether or not I can expect to see an increase after running it for a while now that it's firing?
FYI I did a decarb on the motor just before I lost the spark, so I don't think the poor compression is from carbon buildup.

 

[gm280]

That is really hard to tell. I would run it and see myself. But any answer would be mere speculation at best...

 

[AEROCOOK]

That is really hard to tell. I would run it and see myself. But any answer would be mere speculation at best...

Yeah, kind of what I figured too. I just put about half an hour of slow cruising on it so I'll check and see if there's any change. That cylinder has had some sort of failure in the past, I determined this a few years back when I pulled the head off and the inside (of the head) was all chewed up. I put a new head on it but never bothered to check compression at that time since the motor ran so well.

 

[emdsapmgr]

The chewed up head is a sure sign that the piston chewed up a ring, damaging the head and also the piston's crown. If the piston looks ok, likely the piston is a new one. Unlikely that running the engine will bring the compression up on the low cyl. The compression numbers are barely within the 10% variance for being normal. That would indicated that it's ok to run it. Running it with no spark should not hurt it, assuming that the reason for the "no spark" was an ignition problem. If it was because the carb passages were not supplying fuel-that would be a problem. No fuel means no oil for that cyl.