compression good?

[bretto]

Measured my '83 85 hp Force and I get 115 PSI on all 3 with no oil injected in the cylinders and cold. Is that fairly good? I imagine it creeps up to 120 PSI once it warms up. We ran the boat this Saturday for quite a while with a full load and gear. Pulling skiers and tube for a good part of a day and almost used up only one of the 6 gallon tanks! Seems to be a healthy engine to me, am I right to think this as this is my 1st boat?

 

[Bigprairie1]

Re: compression good?

Well that isn't 'great'...but it is acceptable. Good would be 125-135 and great would be 130-150.
However the most important thing is the overall balance of measured compression. They should all ideally be with 10% of one another...the closer the better (ie: 114-116-118....that kind of thing).
The bummer would be to have one at 130-135 and then have one at 95-100...that wouldn't be good.
So all in all if it runs good and they are all pretty close to one another and if they are all better than 115 (cold)...you're good to go. The only downside of reduced compression (due to age, wear) is reduced power.
Good lucky and happy cruising