General / Tuning 115393M

Hello all. I have a 115393M. Those of you who know that number know its a 115hp 1973 Evinrude. Coming into summer we are once again heading for the water. I made a mod 2 years ago, comprising of a 4psi electric fuel pump and 3.5psi cut off switch for fuel supply. This system works great and we have put 150 odd hours of water sports and stop start caper on the motor trouble free. My main reason for doing this mod was because I use Four tanks and got sick of priming.

Now on the sad note. Im not familier with the tuning process of these perticular motors. Can someone inform me of spark plug gap? Also I am currently running 40/1 mix. Is this high do you think? And the carbs. What is the correct float level and where is it measured from?? Had the jets out and cleaned. Any other things to do to the carbs? I have some trouble cold starting. Its like its getting way to much fuel.

Thanks. Trev.

Re: General / Tuning 115393M

I use 50:1 in mine and have a gap spacing of .30. Im lost for everything else.

Re: General / Tuning 115393M

There are some things which involve tuning that engine. You are working on the carbs, and that's worthwhile, detailed work. I'd make sure the passages in the upper carb body are all cleaned with some type of carb cleaner-which will dissolve dried fuel. (like a Gumout product.) Usually when overhauled, new carb kits are used, which will get you new floats, needle and seat, gaskets, etc. Once reassembled, you will need to check the sync and link-adjust the relationship between the carb opening and the timing advance. If you are not sure of how this is done (it's rather detailed) you should refer to the original factory service manual. If you don't have one, you can get an original from outboardbooks.com. Not much needs to be done on the electrical side. It's all electronic ignition and if you have spark on all 4 plugs, you are good to go.