I have tried a search on TT about dirt in carburator and could not find that much info so I am posting this. I have 2004 WR450F that is plugging up jets, acc. pump etc.. with dirt/silt and when I take the float bowl plug out there is A LOT of dirt. I cleaned everything out and same happened after trail ride that was not too dusty. Sealed every inch of the air box and same. Intake tracts are not cracked and pass the WD40 airleak test. Tried my extra Twin-Air filter and same. Greased the crap out of the inner filter seal and same. My buddies 05 Yz450 does the same (different air filter than WR) and other friend has had same on his 03 WR450. I figure the engine/carb is sucking very hard and the dirt is bypassing the filter/filter oil and this must have happened to other TT'ers. It does it when filter is clean or dirty. Any rocket scientists out there that have run into this problem?