is there a viable solution to low compression?

[johnreidb]

i passed on purchasing a 1980's model 9.9 johnson today because it had low compression on one cylinder and a compression differential of greater than 10% between the two cylinders. they read 75 pounds and 90 pounds cold via a manual starter. it also had a whole lot of black gunk and oil in the cylinders. i understand that low compression is bad, but i am not sure what causes it or if it can be fixed.

if i had purchased motor, what would i have to do to remedy the problem?

could i have resealed the powerhead or put new rings on the pistons? or would the cylinders have to be rebored while adding larger pistons? any of the aforementioned projects are above my skill level and beyond my finances; i am just hoping that someone can explain why bad compression is such a deal-breaker.

thanks in advance.

 

[5150abf]

Re: is there a viable solution to low compression?

If the cylinders are a at different pressures they fire the gas that way too so one cylinders is making alot more power than the other one and it puts alot of stress on the crank.

The cheapest fix of all is to do a decarb, way outside chance that may get you back to your 10% difference, if there was water in one cylinder it woud be a head gasket which is also pretty easy but to find this out you woudl have to buy the engine.

It is probably best to be on the safe side and assume that it needed rebuilt and you saved yourself a big head ache.