I usually run slightly smaller Ah batteries on my bikes, would go for at least a 9 Ah to crank a 750 four.
But unless you
totally change battery technology to something like lithium, you will not get any meaningful size reduction.
there was a guy in sohc4 selling these high tech batts, the advantage in power desnsity (Ah against weight or bulk) is pretty amazing.
forums.sohc4.net/index.php?topic=75570.0;topicseen
tg
