Here is another carb-related fix. I haven't been through all the pages of this thread yet so if it's been posted already, I apologize. I did think this one up on my own, out of necessity.
Last weekend I was up at the cabin & tried to start my ATV (I know, but this tip is good for motorcycles as well!). It started but ran very rich, would only run with a lot of throttle and soon fouled the plug. Once it quit, I smelled gas. It was coming out the overflow. So I know the float needle was gummed up, dirty or stuck.
I tore into it and once I got to the carb found that the ridges on the float needle (like this one below) were scratched up and sticking. Maybe from vibration, don't know why.
So on a holiday weekend in rural central Wisconsin, there was no way to get a rebuild kit on short notice. What I did was carefully rub out the small scratches and burrs with a whetstone, made sure nothing was wrong with the float needle jet, and put it back together. It worked like a charm, ran great all weekend.
I will be getting a rebuild kit and repairing it properly, but this was a good temporary fix. Might come in handy for someone else someday.