115 hp Evinrude will only run 35mph???

[countryboyjlm]

I have a 76 Evinrude 115 hp that until about 5 months ago would do at least 55-60 mph. I had a blown head gasket so I went ahead and had both gaskets replaced. I had also replaced the spark plugs, had the compression checked and everything checked out ok. The motor starts fine and there is no missing whatsoever. It runs great but will only do 35 mph at full throttle. The prop is new and is a 19 inch pitch. I also have tried a 17 inch pitch with no difference in the speed. Is there anyone out there that may have any answers to my sudden loss of power??

 

[hondon]

Re: 115 hp Evinrude will only run 35mph???

This is just an idea, but in that vintage there were both high and low compression head gaskets available for this V4 to compensate for the different fuels that were being shoved down our throats across the country.If the high compression gaskets were installed with the current crappy fuel we are now forced to use ,that could have something to do with it.

 

[MGuckin]

Re: 115 hp Evinrude will only run 35mph???

Are you achieving the same max rpm that you were beforehand?

 

[ledgefinder]

Re: 115 hp Evinrude will only run 35mph???

Those are great motors. Puzzling - could use some more information. How sure are you compression is OK?

 

[countryboyjlm]

Re: 115 hp Evinrude will only run 35mph???

Hey thanks for replying,The head gaskets were the same as the ones that come off.Thats what the man told me that replaced them.and i don't have a rpm gage on my boat ,but it don't seem like it is rebbing up as high as it was.My compression is 130,127,126,116,thats what is was when i had it checked out.

 

[Carphunter]

Re: 115 hp Evinrude will only run 35mph???

I have a 1980 johnson 115, and the same thing is happening to me. I was running about 45mph, (on a 16' dynatrak), and suddenly one day I was only doing 32mph. Found out that I was only running on 3 cylinders. I replaced coils and power pack and it still hasnt fixed, but I have narrowed it down to the sensor coils, or possibly just a bad wire. Anyway, maybe the troubles that I am having will help you narrow it down. By the way, the motor ran great on 3 cylinders, with the only noticable problem being the loss in speed.<br /> Good Luck

 

[countryboyjlm]

Re: 115 hp Evinrude will only run 35mph???

Thanks for the reply,I pulled the sparks plugs wires off each plug while it was running and all of them was fireing,so how can i check if i have a bad cylinder or not.