Honda-SOHC

 
I have just finished putting together my 1976 US import CB 550 K, but I have a carb problem. First time of starting I got nothing on number 2 cylinder,followed shortly by petrol overflow from number 2 carb. No problem remove the carbs that took me three hours to fit, take float bowl off to find floats stuck and LOADS of gunge. Spend next two nights cleaning everything in sight with carb cleaner, took floats and all the jets out. Reset float level and reassembled. Whilst at it took all the others apart as well. Connected carbs up to fuel supply BEFORE refitting to check for leaks..........none or any overflow either. Spent another two hours refitting tonight and...........................still nothing on number 2!!! I have checked points and plugs ( new ) and have healthy spark. Where do I go next...................