Make sure battery is connected properly
Turn key off, see if fuse still blows - tells you where to start looking for short. If not blowing with key off, then turn run/stop switch off, then key on.. does it blow? further narrows down where short is.
Report back with results.
'01 Scrambler 400, K&N
'02 400ex, piped, jetted, K&N, Lonestar +2 A-arms, Lonestar anti-vibe
'02 400ex, DiamondJ +3 A-arm widener, Lonestar anti-vibe
'02 660 Raptor, DiamondJ +2 A-Arm widener, YFZ shocks, LSR anti-vibe, piped, jetted, K&N