Blown fuse

I hooked up my 1978 kz650 to the battery charger just like normal after I did my top end rebuild... Before I hooked it up the battery was almost dead do that's when I hooked it up and everything was normal but the electric starter wasn't working but the switch was flipped ON... Then the lights went off and nothing so I checked the fuse and it was blown so I put another one in tried it all again and the fuse again blew... What could cause a fuse to blow? If it helps it is the fuse connected to the white wire... Thanks for any advice u have

-greg

What blowing the fuse is you trying to blow up your bike's electrical system. As has been stated many times on this forum DO NOT hook the battery to a charger or a vehicle with its engine running while the battery is in the bike. If it's only a fuse you are very lucky. Take the battery out of the bike; charge it at 1 amp, if the battery hasn't already been blown by hooking it to a high amp charger let it charge for several hours then test it. When fully charged, put it back in the bike and go for a ride. Ed

That Fuse to the White wire, 20amp? Should be the Main Fuse for the bike, feeding battery voltage up to the Ignition Switch. If blowing with the switch off, then you got a short before the switch. Or the battery is reversed polarity. Don't ever put in a heavier fuse than rated, unless you want a new harness.