Ok I reckon I am pretty close with my jetting (see below)and it runs like a rocket, snap wheelies and no flat spots. Problem appeared the other day when getting some coaching, the plug appears to load up after any more than about 30 seconds idle. It is only if you let it idle, I rode yesterday killing the motor every time I stopped and had no worries. It generally clears up again after a fast open run (after backfiring and farting) but makes is a real nuisance. If you remove the plug it is heavy and black. Rich? It makes no differance if the adjusting the fuel screw and i have progressively worked down from a 42 pilot to the 38. Maybe a smaller PAJ to reduce the fuel sucked in? see quote re PJ/PAJ ratios from prevoius posts (Jetting Q's - Taffy, JD etc) 48PJ 100PAJ 45PJ 100PAJ 42PJ 85PAJ 40PJ 85PAJ 38PJ 75PAJ 35PJ 75PAJ OR: PJ/PAJ 48/110-125 45/100 42/85 40/70 38/60 35/45 end quote. The earlier ratio's show PJ:PAJ at 38:75 but the later ratios (second list) show 38:60. Has anyone been here before? How did you solve it? It is so close it hurts. cheers.