Just make your own.Use the orginal brake disc ,buy a 22 tooth sprocket or whatever you want and lathe down brake disk to fit snug into sproket and weld.Most welding and some auto parts places sell 30 or 40 pitch sprockets.The biggest sprocket i've seen on a 700 is 17 and it was ran in 3rd and went 45 mph.A 22 would be crazy fast.8" pulley motor and 5 trans.17 tooth trans to 46 axle.