Check you idle is set correctly? Set it on main stand and start it up, let it run for 5mins then turn up the idle screw till the back wheel start spinning slowly on the stand, turn it back a little, slowly, till rear wheel stops spinning, thats the idle set.
I always turn my bike on and let it idle in the morn, then go inside and get my bag ready, put on my jacket and helmet, gloves etc, by then its warmed up and ready to go. If I just start it up and jump on it then it can stall at lights if its cold sometimes. Let it warmup and the choke goes off before you ride, try that?