Check out Shorai battery for lithium ion batts. Can lay them on their side, maybe a small one can fit in the tail section?

 

That should work perfectly thanks

 

yer mines under my tank running standard battery but you lose are box i run k&n style single filter but you will need a rejet to about 120 on main for high rpm

fist off made this



then fitted it here




and a vid with the tank on it


i shortened my loom down as well everything it under the tank and i dont run a fuel pump either