I've currently got mine set to 3.0 and it seems very rich and will start from cold with no choke.
As mentioned by Falcon, it's possible your bike has a Ivan's kit fitted, which will richen up the mixture at idle and requires a 4 - 4.5 turns out to lean off the mixture to obtain a smooth idle. If the bike has been running fine for a good while and has recently started running rich, it's possible the air filter is now restricted and needs either cleaning (K&N) or replacing, so check that.
The above will happen if it's Ivaniased or not.
To find out whether your bike has a kit fitted will require you to, pull the carbs off and check the main jets, needles and if the air bleed holes have been drilled. Many are now Ivanised which is a big improvement, unfortunately owners often don't tell, new buyers/dealers and/or they've been sold on a good few times and the info is lost.