I am thinking I have carbon building up in a 2 stroke/CG. (and the heart break of cerise-isus) The plug gap decreases and she starts really poorly. Well, takes a long while and a lot of UMPH. Then runs great. Plug looks great. Just less gap. Just wondering how folks clean 'em up. Or am I wrong about "CBU" (the dreaded CBU) She is my last working MB and don't want to tear her down until after it gets really cold/snowy.