Just rebuilt engine, 2005 RMZ250, fires right up but idles high with the choke on. Once warm it idles perfectly with the choke off. Pull the choke out and the idle shoots up again. checked and double checked valve clearences and timing. 42 pilot jet, fuel screw 2 turns out, elevation at sea level. Put in new throttle valve plate and installed correct direction. Checked free play in cables. Hot start moves freely. any ideas what would cause this?