Motorcycle Questions? Ask a Mechanic.
It is running to rich on fuel. Check the choke and the fuel petcock
for problems. Vacuum petcocks can leak fuel into the vacuum hose.
Let me know. (I am not Doug but thought you were waiting awhile.
Make sure the chokes are bottoming out if they are plunger type.
Might want to clean them up and lube lightly.
Over half throttle is controlled by the main jet as long as your air flow into the carbs is not restricted. Check the air filters and check for loose jets if it was running well before. If the floats are too high the carbs would leak fuel from the overflows.
You have too much fuel or a lack of air flow by the sounds of it.
Main jets and slide needles handle all the half throttle and up mixtures.
Let me know if the choke plungers were hanging up or adjusted too tight.
Very good, hope it works well now.