There are three jetting circuits you'll need to set independently. That write up above talks about them also. Pilot circuit is startup and 0-1/4 throttle, needle 1/4-3/4 and main 3/4 - full. Of course there are overlaps etc, these are general numbers. Tune them one at a time or you'll drive yourself crazy randomly switching jets.
http://iwan-ae.info/yz250-jetting-chart/yz250-jetting-chart-overview-101-all-offroad-com-jet/