Motorcycle Repair: 1986 honda vt700, air fuel mixture, fuel air mixture

Question
hello! i just bought a honda vt700 year 1986. cleaned the carbs really well. the bike run really well, but on first gear during acceleration, there is a little hazitation.i played with fuel/air mixture screw, but i still have a little hesitation. i also have back fire, but much but little. i don't think i have any leaks in the system, fuel or air. please let me know how many turns on the screw, or what else i should try doing. also, the bike is all stock.  thank you for your time,   roman

Answer
I'm assuming the back fire occurs when you let off the throttle.  That's an indication of a lean mixture to the point it can't be ignited by the spark plug. It could be the idle screw adjustment.  I think on that year you're adjusting the air and not fuel so turning the screw in will richen the mixture and out makes it leaner.  I think a good place to start is 2.5-3 turns out to start.  

It's also possible the intake manifold clamps are loose letting air air in.  I've also seen where someone would over tighten the clamps and pinch the manifold a little causing an air leak.  Also there's a air shutoff diaphragm on the side of the carb that shuts the air off to the low speed circuits during deceleration.  If that diaphragm is bad it will cause backfiring but it doesn't influence the normal low speed air fuel mixture so it won't cause the hesitation you mentioned.       

Good luck
Rich