I own a 1441cc 05 Busa for drag racing and I currently use the bike's standard 12V factory starter circuit setup using a 720CA lithium battery without any problems (hot or cold engine). I start my bike by using a single Full Spectrum Power 720CA lithium battery. This battery has about the same dimensions as a Hayabusa's OEM lead acid battery. Note that few years ago, before 720CA batteries were available, I had an Antigravity YT12BS-16 480CA lithium battery, but had starting issues at times. When the engine was hot from a previous run, I sometimes had to boost the 480CA with Anitgravity's Micro-Start XP-3 200CA Start Battery to get the bike started. My routine went this way: When I was next in line to run and with engine off but already hot, I would have to take my hand-sized 200CA boost battery out of my drag race suit pocket and plug it into the a female connector that was wired into the 480CA battery (like how you would set up a battery maintainer for easy plug in charging). The female connector was accessible just outside my seat. This set up has always worked too. Now, with very powerful 12V batteries available, I obviously prefer the extra power of the 720CA Full Spectrum battery, which by the way, has a boost button that I have never had to use--no 24V starting circuit, no jumping issues at the staring line, just start the bike up.