Presuming the fuse blows when you press starter button?
If so you're sending 12v positive straight to negative or in other words a dead short which you obviously know as the fuse is blowing. Really solution is to inspect your wiring connections against the wiring diagram for your model one by one and you should spot the problem. Have you by any chance mistakenly bolted a switched live to the frame instead of an earth? Did you have the starter switch apart and trap a wire on reassembly?
