"95 115 Evinrude compression?

[danlee987]

What compression should I expect to see on a 1995 115 crossflow V4? this unit has 200 hrs on it. I assume that the 1990 version was the same, but I don't know what it should have been either. I see numbers floating around on the searches I've done saying 120-135# range, but I would like to know what factory #'s were. The 1990 was down to 50-60#.

 

[MOETOROLA]

Re: "95 115 Evinrude compression?

Did you pull all the spark plugs, and open the throttle all the way. also make sure you battery is charged. the pressure dose not matter as much, as the pressure matching at all cylinder. my manual says +or- 5psi all cylinders.<br /><br />This is my first reply, I was just reading the manual. some one else could help you further, or better answer your question.

 

[MOETOROLA]

Re: "95 115 Evinrude compression?

Correction, The difference in cylinders can be +or- 15psi, Also the engine must be warmed up to operating temp, before compression can be checked.

 

[CFronzek]

Re: "95 115 Evinrude compression?

The total pressure does matter. A motor with 85 lb. on a hole won't put out as much power as an identical motor with 120 lb.<br />I'm not sure manufactures stated acceptible cylinder pressures. The ultimate test of a 2-stroke cylinder is a "leak down" test which requires equipment that hardly anyone has. <br />The ± 5 lb. rule tells you that wear on all cylinders is equal and that no cylinders are suffering from damage like siezure, broken/stuck rings etc. But if all your cylinders are right on 75 lb. the motor is still close to the end of it's usefulness.<br />Motors with over 115 lb. have a lot of life left in them. Once a motor gets to 85 lb. it's headed downhill and at about 60 lb. starting can be a problem.<br />Two-strokes are very simple motors but they are much more dependent on good piston/ring seal than a 4-stroke. For shade tree machanics checking cylinder pressures is the only way to keep tabs on your old outboard.