I kinda pride myself at jetting so naturally when I got a 2010 ec300 a few weeks ago I started going threw it. First I adjusted the floats. And then the rest of the jetting. But for some reason the idle would hang a tad. Not a lean idle hang either. The carb was just bring very inconsistent no matter what. Even though the floats were set correctly it would dribble fuel at any angle more than the kickstand. So I used this trick. But it wouldn't seal all the time. That's when I noticed a few tiny pieces of clear plastic in the hole! It's clearly the plastic from the tank when the factory drills for the petcock! Problem solved. I also noticed the air screw was collecting dirt from fuel seeping out. So ill be replacing that too
http://www.youtube.com/watch?v=Kgog_Ng0-2Q&sns=em