91 150 magnum compression?

[crotalis40741]

Hello,
I am new to the site and am looking at buying a boat.
It has a 1991 Mariner 150 Mag 2 on it. I was wondering what would
be considered good compression on it? A local guy told me 100 psi
and no more than 15 psi difference between cylinders.
Thank you for your input.
bob

 

[CrossCurrent50]

Re: 91 150 magnum compression?

Good compression is anything over 100 and it is correct that not more tham 15 PSI between any cylinders. If it has 120 120 130 It,s good if it has 140 150 140 even better. 100 is the low end and should be looked at. Be sure to spray some fuel mix into the cylinders before taking the reading if it has sat for some time. This will give you a better truer reading.