Just interested as to what capacitor you're running there, Gage? Is 10,000 pico-farad in the ballpark? Always thought it'd be champion to make a road-legal small-capacity racer, this project really has my attention.
Sebatron, it might interest you to know that I run my RS125, with full lighting and electric start, on a 12v 3Ah battery. The stock unit was a 9Ah but so far the 3Ah has provided no problems at all. Its a fraction the size of the stock unit and weighs 1270g, as opposed to around 3000g for the larger one. Heres a comparison pic:
http://i73.photobucket.com/albums/i233/boingk/battery1.jpg
Cheers - boingk