I am working on a 80 model yamaha maxim 650 that i got not running. The carbs were leaking causing it to instantly foul the plugs. Compression was ok so i rebuilt the carbs. it runs now but runs rich. I closed the idle circuit off and only let it idle with clean plugs to see if it was the idle or just the main circuits. sure enough idle only it soots the plugs and runs rough. I blipped the throttle and sure enough black smoke. I checked manifold vaccume and the guage bounces hard like a valve problem but i know that running bad from being rich could cause those readings so i just put that info in my back pocket. float level is set via the clear tube method and i atually had the floats probably 5 milimeters low. so im pulling carbs back off and want some advice on what i might be missing. Right now iam thinking about putting the stock jets back in even though the aftermarket ones are at least marked the same size as stock calls for. My curiosity is can too low of a float level somehow cause a high bowl presure or some other wierd annomily or should i be looking elsewhere while i have them back off. Floats seem to be working properly and i cant see any extra fuel leaking while looking through the throats while its running so i am just stumped. the choke seems to be working properly also.