Everytime I take out the bolt at the bottom of the carb to change main jets on my 07 YZ450F I am noticing a more than normal amount of dirt in the bottom. Is this normal? I have checked all boots and seals, cleaned the carb and everything was and is perfect. I can only assume I am getting it from my gas or the can. Is there not some sort of microfilter that can either be part of a funnel that I pour the gas into or part of my gascan to filter out this stuff? HMMRDWN. Last time I checked it before my ride and cleaned it. I only rode for 20 minutes and checked it again. Once again there was a small amount in the bottom. I don't seem to rememeber this problem on my 250F.