What is the proper compression ratio for a 1992 150 hp evinrude outboard?

Answer 1

I was told that there is not a predetermined compression for any evinrude motor. What i was told was that each cylinder on one head needs to be no more that 15psi apart, and the average for each head can be no more than 15psi apart. Say head one has 75, 80, and 85psi-good. head two has 80, 80, 80-good. the average between the two is within 15psi-good. Hope you get that. Say head one has 75, 80, 85-good. head two has 95, 100, 105-good, but the differance between the heads is 20 psi-bad, get what I'm saying? If all cylinders are within 15psi of each other, and above a reasonable psi, say 75 to 85psi on a larger motor, than you should be good. I've also been told that it depends on the motor, had a boat motor mechanic tell me all this as well as giving me an example. He said that he bought a brand new 225 evinrude in 1991 that averaged 85psi a cylinder. So like i said, depends on the motor, If it runs good, fires right up, has power when u want it, doesn't look extremely worn(dry-rotten hoses, rusty clamps, corrosion around the head, excessive oil or water leaks, fried electrical, ect...) then you should have a decent motor. Hope that helps.