Where is the battery on a 2005 Yamaha r6 and how do you replace it?

It is under the seat toward the front of the seat and rear of the tank. Remove the drivers seat to get to the battery. It maybe be necessary to loosen th tank in several spots to lift the tank slightly. On the Yamaha r1 2004-2008 you have to lift the tank as well to get it out. Good luck!