i have an 04 warrior and it has a procircuit t4, and the problem is i dont know where to start jetting, on this thing, i followed the reccomended jetting, 4th clip on the needle, and a 128 dynojet. it made no difference, i still have this flat spot, or hesitation, when i nail it from a stop, as i did after i put the pipe on, the dynojet kit, is for a 1993-03, did they change the carbs in 04? i didnt buy the kit, or pipe being its not my bike, i am only trying to do this person a favor.

 

Having a flat spot off idle could be an adjustment of the mixture screw, or the pilot jet is too small. Heres a good site on jetting that may help.
jetting and symptoms

 

i cant even adjust the air screw on this warrior, it is making me mad, i can turn it for like 1/2 turn in each direction, then it stops, like its stuck, i have jetted many bikes, so i think i know what i am doing, but as far as the screw im stumped, because i know that what it is.

 

Its number 16 in this view.
carb pic
This could be the problem, has it been bottomed out hard? When you finally get it out...if its deformed or bent, it needs to be replaced. It should be fairly easy to unscrew. On this carb its a mixture screw(just symatics), so going out, is richer.
Its possible your friend, tried adjusting this, and screwed it in too hard. It should unscrew all the way, and usually there is an o ring and spring inside, make sure those are there and in the right order.