I'm working on an 85 Nighthawk 450. It sat for a few years and wouldn't rev past 5 grand so I put fresh gas in it and totally disassembled and cleaned the carbs. Now it runs great everywhere past 1/4 throttle but when riding and trying to hold your speed at low rpm's with a small throttle opening it surges. I would think this would indicate that it's lean but playing with the mixture screws doesn't help (from any info I could find, everything 1/4 throttle and below is on the idle circuit). The bike even idles ok with just an occaisional misfire at idle. Also when decelerating from higher rpms it pops like crazy. The only thing I can think of is pulling the carbs off and cleaning them again, maybe I missed something. Anyone ever had this problem?