1969 evinrude sportwin carb question

[Patfromny]

Hello all I am new to the group and very happy to be here. I have a 1969 9.5 sportwin evinrude that my grandfather bought new. It runs like new... well almost. I used it for the first time in awhile this summer and noticed that once you are at WOT if you turn the lean/rich idle knob all the way to lean the engine gives you quite a few more mph. I found this out after using it for a week and fouling the plugs. I leaned it out just to get back to the dock and it was like turbo charging the thing. My brother told me it has always been that way and it would foul the plugs if you didn't do this. I don't remember ever doing this but it has been awhile. After you lean it and the rpms increase you can richen it again with no effect to the rpm. It starts on the first or second pull and runs like a champ otherwise. any ideas?

 

[dkonrai]

Re: 1969 evinrude sportwin carb question

running wide open throttle + lean condition = piston and ring failure. i think that this isnt very good for the motor. a 2 stroke, running @ wot and lean....
im sure some of the fine folks here will agree.

 

[Patfromny]

Re: 1969 evinrude sportwin carb question

running wide open throttle + lean condition = piston and ring failure. i think that this isnt very good for the motor. a 2 stroke, running @ wot and lean....
im sure some of the fine folks here will agree.

That is after all the reason I'm here asking for advice.

 

[dkonrai]

Re: 1969 evinrude sportwin carb question

two strokes lubricate the engine by means of mixing oil with the gas. so a lean mix will not give the motor enough oil. so no oil, means bad for the pistons, rings, bearings. reason its running better lean is prob due to needing a carb cleaning. i never tried running a motor wot, then turning the knob to full lean, i would turn it the other way, to rich to help lube the motor.
just me.
dino

 

[tjhamms]

Re: 1969 evinrude sportwin carb question

Sounds like you need to properly adjust the carburetor. Do a search on here for "Joe Reeves carburetor adjustment" and follow the instructions as per your carburetor.

 

[Patfromny]

Re: 1969 evinrude sportwin carb question

Sorry Guys I feel I should clarify and maybe expand on my first post. I am a good mechanic and in a former life I street raced and have restored several muscle cars. I'm in the middle of a conv. Firebird project right now. I do understand the effect of leaning any engine at any rpm. Playing with nitrous teaches you that the hard way:laugh:. I'm just new to the outboard motor world.
I agree that I should Look at the carb but it runs well at all other times and only needs this leaning step to acheive top rpm. once there I can fatten (richen) the carb with no effect on rpm. Also the engine fouls the plugs if mixture screw is left alone (at best idle setting). This tells me something inside the carb is sticking or clogging but carbs don't continually clog and unclog. Maybe there is an advance weight or something like it sticking . I would hate to go through the carb put it in the lake and have the same problem. Is there anything ignition wise I should be looking at or do you guys think it's all carb? Thanks tj for the thread to read. I will look for it right now