I just did not find a way to turn the idle mixture screws of the middle carburators when the carbs were on their place. So, no adjusting when the bike was running. I fixed this with drilling a 2mm hole in the middle of the screw, put a bicycle brake cable in it with flux and heated and soldered them together. Also I but a couple of abicos in the cable before soldering it, to help fasten the cable with carb bowl screws. Then just put all together... No need to write more, I'll attach 2 pics, they should show this clearly
Now it is easy to adjust the inner carbs also when the bike is running. Not a perfect solution, but a cheap one.