I've had many problems with my 1984 big red not idleing. I would remove the carb, clean the jet & it would be fine for awhile. The tank was rusty so I bought a plastic tank hoping to cure this. I then had trouble with the float sticking so I bought a carb kit & installed it, adjusting the jets the same as the old ones. It idles ok but when I speed up it acts as if it is starving for fuel & jumps. I've tried loosening the gas cap thinking it was a venting problem. The plastic tank has a cap with a vent hose. I also put a new plug in it. Any suggestions? Could I have a jet mis-adjusted?
Thanks,
Greg

 

I would check the slide and needle assembly to make sure the needle is sitting all the way down(against the clip) in the slide. If that looks good, try raising the needle up 1 knotch(lower the clip), and see if that helps. I have never had a carb apart on anything that old so I'm not real familiar with them, but I think all the theories remain the same.