ignition switch wiring problem

[rall275]

1988 BMW K75C

I replaced a right combo switch and all was going well.  Had to remove the cockpit of this C to get her in.  Put everything back together.  Tried connecting negative battery cable and it sparked and I have some wire damage. 

What happened?

I'm not that good with electricals, but I've done a lot of work to this bike and it runs nicely.  I changed the combo switch because ever since I've had it the kill switch portion did not work.  Then, on occasion my bike would die while running but would start right back up, so I suspected that start/kill switch. 

Photos will show this:
A red wire in the loom in the relay box had melted insulation.
This wire went to the connector under the fuel tank.   Both parts of the connector show the same wire experiencing heat damage.  The wire going to the ignition switch was hot, and there is damage to one of the pins on the ignition switch.

My suspicion is the ignition switch was bad or a contact had broken on it.  I did have to carefully let the ignition switch and the pad it connects to dangle during my combo switch swap.  Maybe that weakened a connection on the ignition switch?

Any advice welcome on how to determine the cause and what you'd recommend for the cure.

I'll send photos showing this damage. 

wiretobottomconnector.jpg (52.63 kB . 432x576 - viewed 59 times)
igswitchconnecttop.jpg (68.23 kB . 768x576 - viewed 61 times)
ignswitch.jpg (47.46 kB . 432x576 - viewed 62 times)
relay box.jpg (70.44 kB . 768x576 - viewed 61 times)

[Laitch]

Was the ignition switch firmly mounted to the switch pad and the pad bolted to its handlebar mount when you attempted to attach the ground cable to the battery? If it was still "dangling", the switch contact for the battery positive cable might have shorted to ground on the fork or frame. A short like that in an unfused wire would be likely to start a fire.

[rall275]

Thanks for the response. 

Yes, the ignition switch and pad were firmly attached to the bike when I attempted to reattach the negative terminal to the battery. 

[Laitch]

Was the positive terminal connected to the battery before you attempted connecting the negative terminal?

[rall275]

Yes it was.  Hope I didn't screw up by doing that!

[Laitch]

You didn't screw things up if the positive cable was connected to the correct battery terminal.