something done before....
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1259644714BigCrank is a battery I can recommend.
They sell various sizes
You'll have to pick a size for your use.
You plan on using accessories? Don't do it.
You don't go very far between stops? Don't do it.
Can't push start? Don't do it.
For a standard commuter with a minimum 30 minute ride at superslab speeds, you can down size your battery as it's going to be charged with every use.
If you are going to be a delivery boy with dozens of stops and 5 miles inbetween each stop, no way are you going to keep it charged and you might not last the day.
Our #15 battery has
• 12 Volt, 14 Ah, 220 CCA
• 5.25"L X 3.50"W X 6.56"H
Next size down is a #12
• 12 Volt, 10 Ah, 180 CCA
• 5.88"L X 3.44"W X 5.13"H
Still smaller is a #9
• 12 Volt, 8 Ah, 120 CCA
• 5.88"L X 3.44"W X 4.19"H
then even smaller are the LiFePo batteries (don't go less the 8 cells)
BM Part #: LFX12A1-BS12
Capacity: 12 Ah / 155 CCA
Length: 5.83"
Width: 2.60"
Height: 4.13"