I really wouldnt weld it back on, i could never get it to work.
I found the best way, is to cut the cable (at the end with the metal bit), and crimp a power fitting (spade connector), so that its just the crimp bit on the cable.
Crimp, crimp, crimp away, until its rock solid. Heat with blowtorch, and apply solder.
Then just file it so that it fits into the throttle mechanism?
And yer right, howstuffworks sucks..
Ill help, if you need. Im surprisingly doing a similar project, only its with a foldaway pushbike, and an engine from a boat.