1 Answer. 2005 kx250f wont idle.will idle fine w/choke on.carb cleaned,new idle jet#41 mixture screw 2-1/8 turns out still no change. pops on deceleration.runs good top end.Posted by bwilke55 on.1  Want Answer 0.005 kx250f wont idle.will idle fine w/choke on.carb cleaned,new idle jet#41 mixture screw 2-1/8 turns out still no change. pops on deceleration.runs good top end. Posted by bwilke55 on. 1  Want Answer 0.