I'm new to riding, recently bought a 1999 GZ250 hardly used (with 2914 miles on it), as a starter bike, from a mechanic I know who was storing the bike for 2 years. He put a new battery in it before I bought it (from Battery Source, a 7L-BS sealed 12V 6Amp). The bike started instantly and ran great, but the battery would be dead in a few days needing to be recharged to get the bike to start. When I bought the bike, the same thing happened - if I could start it after recharging the battery it ran great, and after riding for 20 miles, if I shut it off, the battery would be half dead and not have enough juice to turn the starter fast enough to start it, or you'd hear the clicking and the starter would not have enough juice to turn. I returned the battery thinking it was defective and the guy in the store agreed after he put it on a load tester and I got a replacement. The same thing happened - the first time I used it the bike would start and run well and then it if was shut off, the battery acted as if it was dead and hadn't enough juice to turn over the starter. The headlight goes on when the key is in the on position, and the battery voltage would drop to 8.5-9V even before hitting the start switch. I recharged this battery multiple times and eventually brought it back for another replacement, being on the 3rd battery now. I've cleaned thoroughly all the connections I can see on the battery and starter, I can't see any frayed wires anywhere, I don't leave the rear parking light on. and there's no open circuits anywhere with the key in the off position. The bike will start instantly from a portable battery pack but not from this battery. The guy in the battery store says the batteries are working fine after testing them. It's hard to believe that 3 new batteries could be defective, but I can't find anything obvious wrong with the bike. I know the bike only puts out the equivalent of a trickle charge when it's running, but is this the right size battery to use even though that's what's reccommended? Is this battery I'm getting not large enough, is anyone using a larger capacity battery? Or is the problem somewhere in my bike I'm overlooking? Any suggestions would be appreciated, Thanks.