If you need a battery I would look into something like this.
http://search.ebay.com/270535582829
They last at least 2 to 3 times longer than a regular acid battery. I have left them in little bikes and scooters over the winter and still have them start in the spring with no battery tender. You might even be able to find them local.
Smithers - I have a 79 Express and run it with no battery. That little scooter used the headlight as a regulator and with no battery it blew right away. It's always funny to see if someone can figure out how to start the Express.