I have an 06 with 25,000 miles on it that I bought new. I have Cobra Speedsters, BAK, stock manifold, no AIS, at sea level, Main - Mikuni 170, needle 4th groove, Stock 35 pilot, PMS 2.5 turns out. I have run this configuration for over 22,000 miles, get 38 mpg city, 44 highway. I have changed plugs regularly at 8,000 miles and they are slightly ash gray to white, no erosion of the electrode, with some black on the inside of the threads indicating somewhat rich in idle circuit. She WOT's out perfectly so no lean. I have not put her on a Dyno, but from the way she runs the mix is pretty good. As for the float an 04 and up the level should be as I recall 1mm above the mating surface and that is where mine is. I have had the carb off at least twice to check the needle valve and it is clean. I have not experimented with lowering the float level, but that is probably the only thing I have not tried. Thanks for the help, but feel like I have pretty much tried it all short of replacing the fuel pump and pressure sensor. This is not a regular occurence it happens perhaps 3-4 times per summer so not such a problem. I am sure it related to heating of the carb and expansion of fuel...I have thought about shielding the carb and seeing if it solves the problem. You will see my name on puking strings for the last 2-3 years, but always open to new ideas.