Ever since I got my 02 YZ426 there has been a pesky off idle bog that I cant seem to get rid of. Now before you write this off as another one of those old Yamabog issues, hear me out. First of all here are the specs: Stock motor & headpipe ESeries S bend Unifilter Stock Needle, clip in middle 168 main 42 pilot Zipty Fuel Screw BK mod the "NEW" Powernow everything else on the carb is stock Conditions: 70-90 degrees/ 1000-3500ft elv Heres the story: I rode it a few times before the powernow and it was never crisp as you first cracked the throttle. I added the powernow and the condition seemed get worse. If I just went from closed throttle to over 1/4 swiftly the bog was hardly noticeable. But when I got on tight trails and had to work the clutch & throttle (just barely cracking it rapidly, just to keep it from stalling) the engine would seem to load up or gasp and try to die. As soon as I stopped it would be fine and continue running. It will do this in neutral as well as lugging at low RPMs in gear. Bumping the idle up would help, just because revvs would be higher as I chopped the throttle & got back on it again. The condition seems to worsen as the engine gets hotter. This is driving me nuts, nothing has worked. Ive done the BK mod, AC pump works fine, gone from a 40PJ up to a 48 in all the condtions I listed above, still no change. I adjust the fuel screw correctly (Idle high & turn for peak RPM) but nothing can get rid of that bog. It runs great everywhere else. Yes my filter is always clean. All this usually happens after you let the bike warm up and ride it around for about 10 minutes. Has anyone else had this problem?