I used a ball joint separator tool to get mine off. It's a long piece of metal with a forked end that you can buy at like Kragen. I tried some of those pullers they had and none fit right. You stick the forked end between the spindle and ball joint and hit the other end with a hammer until it pops loose. This tool usually breaks ball joint boots though unless you're really careful, but if you have new a-arms then who cares?
'02 Yamaha Blaster - '03 Front Hydraulic Disc Brakes, Elkas on the Front, +3+1 ASR a-arms, DG Bumper, PB Phantom Exhaust w/Spark Arrestor Kit from ALBA, Renthal Bars, Premix, No Air Box Lid, Uni Air Filter, UM Swinger Skidplate, AC Nerf Bars, Holeshots all around