They will fit but you're going to destroy your balljoints and possibly get yourself hurt. The YFZ shocks have too much travel for the stock Blaster a-arms. I think they will work if you have LT a-arms though.
Stock for stock though I'm pretty sure no suspension parts from a YFZ will work on a Blaster.
'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