Hey I have an 06 crf 450, it's been sitting for a year. The valves were adjusted before it sat. It started but wouldn't idle and cut out. I tore the carb apart, cleaned it thoroughly and now it runs better but still not right. It's backfiring at a quarter throttle and the idle is very low and then goes high by itself. I adjusted the fuel screw, and there is no exhaust leaks. Any suggestions??