07 kx250f
 

Hey guys new here to the forum. Names mike. I have searched high and low but can't seem to figure this out. I just bought a new to me 07 kx250f. I have a kfx450r atv. So new to the whole carb. I can do them just not used to all the stuff on them. I can work on my son's crf50 but that's about as far as it goes. Ok here is my question. The bike starts idles good with choke out now when I let off choke dies instantly will not idle for anything. When I keep moving throttle I can ride it. It bogs a little at first then it's ok but the thing backfire like a bunch of fireworks going off. I checked the timing it's good valve clearance us off just a tad not enough to do that I don't think. Spark plug tip is white it's gotta be very lean! Now my question is how do i know what to change which jet and so on please help I'm lost!