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Dirt in the carb lid on my '05...Where does it come from?

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I have exactly 4.1 hours on my new '05 450. I was reading a post in the 250 forum concerning dirt/dust in the carb causing the valves to crap out. Well, I thought I would take my top cover off of my FCR tonight to check it. I had a fine layer of dust imbedded in the oily surface of the lid!!! No!!! I am assuming that it was dust sticking to the oily surface. But where is it coming in at??? The intake tract was clean as can be and I cleaned and oiled the stock filter with UNI oil before even running it!? I don't think the air silter is letting it through... I hope it was just the top carb cover leaking a little as suggested in the 250 thread. I filed the "seating studs" a little to allow the o-ring to compress a little better, and applied a coat of lithium grease. So, I hope this will take care of the source of dust...I will post in the future to let everyone know.

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I just got an 05 250F. After 1 ride there was alot of dirt in the gas tank. Not sure how it got there but even though there is a filter this might be where some of the dirt is coming from :cry:

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Regardless of how well you seal your airbox and carb, if you're riding hard, especially in dusty areas, the big 4 strokes will ALWAYS suck in a little grime into the carb. It's just due to the velocity that these engines suck in air. As long as it's not a WHOLE BUNCH of dirt being sucked in, and you routinely clean your carb, it shouldn't be a problem.

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I think furryballs is right.

I also think the dirt past the filter while never good was more of a whipping boy than the acutal reason for the valves going bad in the early CRF's. Since everybody fixed the air boxes, including Honda, the valves themselves along with under rated springs is more the problem than some dust.

My dads Triumph ran wide open velocity stacks and ran for years that way..... :cry:

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I have also found dirt built up under my carb cap. Sometimes its so bad it works its way down the slide. I remember someone on TT saying it seeps in throught the hot start at the carb :cry: I don't think its normal,only a few people have posted this problem that I know of.

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