g9m3c

First off, I am building an off road go kart with a 700cc engine off of an '86 Yamaha Virago. The problem lies in my final drive. Chain drive is just about the only feasable option for a go kart, with out spending a lot of time and money, not to mention hours of fabrication. However, as you probably already know, my engine is shaft driven. I was wondering if any of you have an idea of how I can transfer power via the shaft driven engine to a chain driven axle. Is there anyway I could just retain the swing arm, or at least the part that the shaft goes through, and just add some type of sprocket where the rear wheel would be? Then I could run a chain going to another sprocket on the axle. Any ideas/tips/experiences? The only problem I have run into on this entire project is the matter of my final drive, I really would appreciate even speculation as to what I could do with this!