Merc 75 compression pressures

[TheOrs]

Hi

Anybody know what compression pressures I should be getting on my 1992 Mercury 75 3 cyl. (clamshell cowl)?

I have measured it at 9.2, 9.4, 9.4 Bar (about 135psi). This seems a bit low to me but I am not that up on 2 strokes.

I was checking because the engine seems slightly done on power recently. What I did find was a very poor connection on the battery kill switch; poor enough to stop the electrics working occasionally. Would this have been likely to affect engine performance once the engine was started & running?

Thanks

The Merc pressures are normally 125 psi, however before you get worried go and check the pressures again just to be certain. Its normally the middle cylinder on a 75/90 that goes down first, something to do with cooling like early Kwaka 2 stroke tripples.

Since its a 2 stroke it isn't the end of the world to take the head off and have a look.

P22

[TheOrs]

Originally posted by Pacific 22
The Merc pressures are normally 125 psi,

Ta very much; I guess there's not much wrong with my compressions then.

[The gArfish]

Originally posted by Pacific 22
Its normally the middle cylinder on a 75/90 that goes down first,

noe itt aynt yew nobbur. itts de fkin topp wan. yew axe peet sevun. heel tel yew.

gArf