you should get a couple 6s 5000mah 20c turnigy lipos. they are $60 each and they should be more than enough for your setup........unless fat bastard (from Austin Powers) wants to take that bike for a spin.
They say a good mechanic only needs 2 tools - WD40 & Duct tape. If it moves, and its not supposed to, duct tape. If it doesn't move, and its supposed to, WD40.