I put the physically largest and most powerful 14 amp battery in my 500 that I could shove in there. It did not help. I will say, however, that no matter what battery you use it had better be fully charged. My bike is an absolute bear to start in colder temps. It's not a problem for ME because I'm a fair weather rider in my old age. I still find it very annoying. It seems as tho it fires & takes off immediately when it starts. If it doesn't start on the 1st turn or two I stop & start again or I'm just cranking for no reason. In the cold it will fire exactly one time & then no more. Eventually it will fire twice, then after more tries it will fire three licks. Around there it takes off. Seems to me like as soon as it wants to fire the starter bails out so it takes off as it's ready or it just dies. It's not the old kicking out bendix feeling I am used to my whole life, the starter just leaves the game, I can't really explain. It's like the starter needs a one second delay before cutting out and it would start just fine. In warm weather it starts instantly, even after sitting long periods of a week or more.