Omc 115 evinrude compression

[Jchevy1990]

I was wondering is 100psi in all cylinders of on 1993 115 evinrude crossflow bubble back .plz need help will run 35mph at 5000rpm with 17p prop

 

[DaleH]

Gauges vary, but I think that's fine, no large variation, cylinder to cylinder and from left bank to right bank.

If not mistaken, the normal operating range is 4500 to 5500 RPMs. Current thinking is that the engine should run in the upper range of the normal operating range, or 5500. I believe your model is the bubble back engine (the '93 Johnson is) which does breathe better at higher RPMs.

NOTE this ... propping to wear the 'right' prop is better for the life of the engine than the pure pursuit of speed. I'd drop to a SS performance prop and possibly raise the engine height, if too low. I prop to be 100-200, NO MORE, off the max RPMs with all typical gear carried, 1/3rd fuel and me aboard.

 

[CedarRiverScooter]

You might want to try OMC engine cleaner, maybe rings are a bit gummy. Other than that your 2 choices are use it as is, or rebuild.

 

[Jchevy1990]

What gets me Is I called about a rebuilt power head for my engine and he said all motors comes with 110psi new

 

[Jchevy1990]

Daleh I'm running a 17p power tech stainless steel cupped prop

 

[Pappy]

What gets me Is I called about a rebuilt power head for my engine and he said all motors comes with 110psi new

Within 10% is the normal rule on compression. OMC stated this in the books. They knew that compression gauges varied wildly in the field and it is very true. My gauge does not read the same as the other mechanic we have at the dealership for example.