Compression on a 1975 Evinrude 70 hp

[iboats625]

I have a 1975 Evinrude 70 hp. I just checked the compression on all 3 cylinders and it is 150# on each. Is the too good or are they too high? I used a brand new compression tester.

 

[TraskRiver]

Re: Compression on a 1975 Evinrude 70 hp

Looks good to me. Top of the spectrum.
my 1979 75hp was 145 across the board last I checked.
Possible it has been rebuilt lately or little/light usage.

 

[iboats625]

Re: Compression on a 1975 Evinrude 70 hp

Thanks for the comment. Motor had not been been used since 1992. I have been trying to get it to run reliably this summer. It starts ok but once put into gear it dies. I have replaced the coils on all three cylinders and rebuilt the fuel pump made other adjustments to the carbs but it still refuses to run under a load. I see from this form that it is not any uncommon problem. Next I am going to check the spark and then dig into the carbs if that does not solve the problem. If that does not solve the problem I do not know what I'll do next.

 

[phipps]

Re: Compression on a 1975 Evinrude 70 hp

Clean the carbs.

 

[Chinewalker]

Re: Compression on a 1975 Evinrude 70 hp

+1 on carb rebuilds...

 

[boobie]

Re: Compression on a 1975 Evinrude 70 hp

The spark should jump a 7/16" open air gap on a tester.

 

[TraskRiver]

Re: Compression on a 1975 Evinrude 70 hp

Link and sync after the carb rebuild