So, fellow Instructables denizens, I have a riddle for you:
I'm currently planning a future Instructable on making my own scooter out of an old mountain bike and a chainsaw, similar to what Dave (that crazy Canadian) did with a weed whacker motor:
http://www.youtube.com/watch?v=uruaRsCHvk4&feature=channel_page
By my calculations, I would need at least an 80 tooth sprocket (more would be better) on the bottom bracket, driven by a corresponding 6 tooth sprocket on the clutch of the chainsaw motor.

Does anyone know where I could find a matching set of sprockets and chain for such a project? I've tried looking in http://www.partsforscooters.com/All-Parts/Sprockets but making sense of all those chain numbers etc. is giving me a headache. So send me a message/comment if you can make sense of that sort of thing. In another video, Dave recommends looking up an industrial bearing supply store. Would that be a good place to look? If you can help me, I'll be sure to credit you. And if I win that laser cutter, you're welcome to come use it any time!