BurnPgh wrote on 10/13/11 at 14:16:38:YTZ7S = 4.44" x 2.75" x 4.13", 4.6 lbs, 130CCA , 6Ah, list price $137.50
The YTZ7S is powerful enough, much smaller than stock, much lighter than stock, and MOST IMPORTANTLY can be had on ebay for $30 for a chinese cheapy.
If you opt for this battery i recommend you have a battery charger as well. You can start and kill it over and over about a dozen times before it'll stop responding but dont leave your lights on unnecessarily. Only takes about 30 minutes to drain it enough that the bike wont start. I found out when chasing an electrical gremlin.
Seconded on all parts. I use this battery and tuck it away on the exhaust support under the swingarm. If you take a lot of little trips you can hear it noticeably get weaker, but it has been working well for me so far (just a few months, mind you).