75 evinrude 70hp problem

I have a 1975 evinrude 70 hp. my first boat and motor. It hesitates at low rpm just puttering along and when u push throttle down it bogs and spits kinda like its missing. its fne when you get it past it and works great at wot. it seems like the longer u putter along the worse it does it and it will die out if you let it idle in gear too long and try to accelerate. i had all the carbs apart and everything looked good and i had to adjust the floats to the correct 1 1/8 drop they were all wrong. thought that may have solved it but no dice. i replaced all the plugs and wires and wire ends where the spark was jumping out of the wire. im stumped as i want this engine to run good i dont know if im asking too much from a 1975 engine or if 2strokes just sputter like that. and ideas what it could be or a place to start.

i cleaned the carbs and adjusted the floats
replaces all the plugs 3
replaced wires and boots. they were the type that the wire screwed in the coil.
vent is open on the tank

Re: 75 evinrude 70hp problem

What's the compression on it ??

Re: 75 evinrude 70hp problem

I'd propose the carburetor low speed is too lean.
J

Re: 75 evinrude 70hp problem

Il have to check the compression tonight. The carbs all have fixed jets on them. How would I clean up the low speed mixture.

Re: 75 evinrude 70hp problem

Make sure the thermostat is in place. Had one awhile back that I chased around various carb issues because it would sneeze at idle and eventually stall. Turns out the motor simply wasn't ever warming up - a previous owner had removed the thermostat entirely. Installed a thermostat and the motor ran 100% better!