200 cca is the stock rating.
I have herd of people running a Yuasa HD Grizzly battery. It is rated at 320 cca. I think you have to rebend the battery hold down bracket and maybe make a longer Pos batter cable from the starter relay to the battery. Shouldnt be to tough though.
That is the battery I am going to get when mine goes out.
03 Limited Edition Raptor Hot Rods 720cc Stroker, Megacycle x-4 cam, Sparks 6X Big Core Exhaust, 35mm Keihin FCR's.
97 Yamaha Banshee - F.A.S.T. Dune Ported 4mill Stroker, CPI Pipes, Keihin PWK33's, Direct Drive Lockup,
158 main jets, CEL Needles on the middle clip, 45 Pilots.