My float height was wrong on the 250, when I bought it. It was set so that it hardly stopped the flow at all. It was new to me, so i had no idea about what it was doing to performance. I did have a cold-foul deal, that i could bet on. Almost every start-up resulted in an eventual fouled plug, after trying to use the throttle just right trying to get warm. Too much gas=fouled. Not enough = fouled. Then with a new plug, started right up and rode the rest of the day. Finally let my buddy work on it and, he found the float adjustment to be way off. Bent the little tabs so that it shut off the valve right, and bammo, now I change plugs when I feel its been so long I can't remember when I put it in there. As for performance, I am not sure, I think it died on me less once fixed. Not sure though if that was the issue because I was throwing the book at it.(pipes, silencers and gearing) I think though, Bdi is right on with the set the float the way it supposed to be set, and tune with jetting. Actually the needle adjustment is pretty big factor to tweek on, but that is another topic altoghter.