idle varies when cold

I have a 09 kx250f, with full yoshi system and carb jetted per jd, blue needle 4th down, 85 main, 42 pilot and oem 55 leak jet, has done this even before mods with stock exhaust and carb settings, will fire right off, high speed idle, then will idle down too low and stall, I have been turning up idle screw until warm then will run fine rest of day. ps air/fuel screw out 1 3/4.

Sounds like an airleak.

Check that all parts are still on the fuel screw, spring, washer and micro o-ring.

Make sure that the hotstart closes completely.

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