i went to start it today. and with the choke pulled out it revs sooo high and it wont idle with the choke pressed in. i give it gas in nuetral, with the choke pressed in after fully warm and the revs stay high for a few seconds then they come down to a low idle then a stall, even if im in gear riding and want to cost to a stop the revs stay real high then go low after a few seconds. when fully hot and i pull out the choke the revs shoot up really high and stay there. its really weird and never rode like this before. i unscrewed the little 16mm cap on the bottom of the carb and it had some black dirt in it. i checked the filter and it was sealed and clean. the gas was filled fresh and with a new gas can, it just sucks cause i have no clu why it running like this or how the carb even got dirt in it., so whats wrong with my bike?