In 2001, the bikes were fited with a revised starter motor gear ratio that drew less current and made it possible to start the bike using a smaller battery. The starter gearing on the early bikes are not well suited to the smaller batteries.
Standard battery 1994 - 2000 model years:
Yuasa YB16AL-A2 (16 AH, 200 CCA, 11.5 lbs.)
Standard battery 2001 - 200X model years:
Yuasa YT12B-BS (10 AH, 125 CCA, 7.6 lbs.)
[Edited on 1-13-2005 by Shazaam!]