[longrider]

More than likely you have a bad stator. This is probably why the bike was sitting in the first place. I do not wish to insult your intelligence but I'll continue anyway.

The stator is the bikes "alternator". Unfortunately, on this vintage bike, it is inside the engine case. If you are going to do the work yourself, prepare to research, test, and roll up your sleeves, and wrench-you have some work ahead of you. This site has many posts on replacing the stator. Get busy.