A lithium battery works differently than a lead acid battery. They can't be teatsed the same way. Most manufactures use a comparison rating. Giving buyers some idea of comparitive capacity. Read the onfo from the battery seller provides to decide what battery you should use. Some seller have a reference list that will help you decice, Look up your bike and the list reccomends a battery.
I had a Ballistic 8 cell battery in my 750 kitted 75. Rated at 12 a/h and 275 cca's I think they lowered the cca's to 240 now. It worked very well. As I am Carbon mentioned they don't like the cold. Thwey also don't like to be drawn below about 2 volts. Like if you hit the engine stop switch, jump off the bike to rush to the bathroom and forget to turn off the key and run the battery dead.
They also don't like to be over charged.
Anyway I destroyed my 8 cell and replaced it with a 12 cell. It's case size matches a stock battery, is 12 a/h with 360 cca's and weighs about 2 lbs.
It works much better.
American Iron just finished up a two part article on batteries. First part lead acid, second prats Lithium.
Leo