06 450R will only run with choke all the way out

[300ex13]

I just picked up a used 06 and its very difficult to start and keep running. It will not start or run with the choke pushed in, but will run and idle with choke all the way out. I just put in a new stock air filter and it starts easier, but the choke still needs to be out to run. I was told by the previous owner that the carb had been tweaked on and I am thinking this is the culprit, just not entirely sure what adjustments I need to make. Also, I should probably swap the spark plug, just not sure what to run (no owners/service manual). It is 100% stock and I plan on only riding trails, no racing. Any help is appreciated!

[blacknblue#2]

Your symptoms are describing a lean pilot circuit. Either from too small or a dirty pilot jet OR someone has turned the air fuel scre in too far. The air fiel screw is located on the bottom of the carb, It will have to be off to see it. I would start 2 turns out on it for a starting point. Also be sure your idle adjustment isnt backed off too far. Its a black plastic knob under the gas tank on the right side of the quad (if your setting on it)

[300ex13]

I took the carb off this weekend and the screw was all the way in. I turned it out 2 turns, replaced the spark plug and reassembled. It starts easier and (after adjusting the idle screw) idles better than before, but the choke still needs to be out in order to run. Do I need to take everything apart and adjust the screw for say 2.5 turns out or is there another minor adjustment to try?