Frame Welding

The right hand side petrol tank bracket has cracked off and I want to weld it back on but I am in a bit of a hurry. I want to take the bike away this weekend and only have one evening free to work on it so I want to minimise the time spent dismantling and rebuilding.

I am worried that MIG welding will destroy the bike electrics if i leave it all attached while welding. Will it? How much do you think I need to dismantle the bike to work safely on the frame? Thanks

Just to be safe disconnect the electronic ignition pos and neg (if you have one) and maybe the zener diode(s) and the battery. That way you are covered. Other than that I can't think of any other issues.

Put the ground right next to the mount.

I second Cookies statement.
If the ground is ill placed and go through parts of the bike where there are bearings then there is a possibility for arc passing through bearings…not a good thing.
CNN

Yup, like the neck bearings.

Thanks chaps, it is all done and it went without a hitch.

There was a slight catastrophe when I completely discharged the battery 50 miles from home because I'd neglected to connect the rectifier back up but a nice Italian man lent me his battery charger so it all worked out in in the end.

Good on ya Bertie. Breaking down makes the trip more interesting and can often restore your faith in human nature.