I need to do some work on the carbs as my Superfour is running very rich at the moment, does anyone know the best mixture screw setting for the carbs please?

My mixture screws are very far out at the moment, 11 turns out, I suspect this is why the bike is running so rich!

Screw the mixture screws fully in ( not excessively tight) then turn them back about 2 turns this is a base setting, I used a Gunsons colour tune to determine the air/fuel mix and am happy with the result.