'84 Evinrude 9.9 Compression

[mafhuntfish]

Hi - I need to know what the compression should be for an '84 Evinrude 9.9 - I have a Seloc manual for this motor, but I can't find a compression value in it. Thanks for the help ..... Mark

 

[lindy46]

Re: '84 Evinrude 9.9 Compression

There aren't any official specs but if you have 85-90psi or better with less than 10% variation between cylinders, you should be good to go.

 

[mafhuntfish]

Re: '84 Evinrude 9.9 Compression

Thanks lindy46. Thats what I thought, but I wanted to be sure. Both cylinders are at 60 lbs. Could this be the reason for it to be really hard to start cold?

 

[lindy46]

Re: '84 Evinrude 9.9 Compression

If they're both the same, put some Seafoam in the cylinders and let them soak overnight - could just be stuck rings. I did this with my 5.5hp and picked up about 10psi, and 70-75psi should allow motor to run ok.

 

[mafhuntfish]

Re: '84 Evinrude 9.9 Compression

thanks again - Will try the seafoam