Ok, I have a problem with my 2002 WR426. I seem to be getting dirt in my carb/jets somehow. It doesn't seem to be coming in through the air cleaner as the tubing between the filter and throttle plate are perfectly clean, not a spec of dust. Yet when I open the carb there is dirt inside. How? All my vent tubes are factory length and hang under the bike. I clean/oil my filter every other ride. It isn't even that dusty where I ride. The bike will run fine for weeks then it will suddenly get a bad fuel problem and won't get better until I take apart the carb and clean it all. HELP!!!