what would cause my little 200 cc quad not to hold a charge in the battery?

 

Either a bad battery or you have a draw. Those are about your only two choices.

To test for a draw take the - cable off and read amps through your VO meter. Or if you don't have a VO meter just take a cable off of the battery and just touch it to the terminal of the battery and look for a little spark.

 

One more thing to check is the charging system of your quad. Any battery will have some amoutn of drain even if the terminals are connected, even just by sitting. To check the charging system, check the voltage reading at the battery terminal while engine is idling. It should read:
> 13+ volts or higher when idling.
> 13.5+ or even 14+ volts when revved up.