I seem to have the same problem. When I disconnect the headlight the bike runs better. I took it to a shop and they said the only thing they can see is that the stator is not producing enough ac voltage. They said it is running at 65 volts ac and it is suppose to be at 75 volts ac. Did putting a new battery fix your problem? My battery tested good.

 

it sounds like to me that the pilot screws of your carb got dirty. Those screws control how well the bike idles and low throttle.

 

Well it only starts stalling when the cooling fan comes on. When the fan turns off the idle goes back to normal.

 

Can anyone tell me what their voltage is at idle and 5000rpm?(2000 cbr 600 F4)

 

Nothing less than 14 volts at 5k. High 13's at idle.

 

Some how electrical system is getting bogged down when the radiator fan is on. I agree, I would check battery, voltage regulator and alternator. Good luck!