i am looking at buying a ds650, the guy says the battery drain's within 2-3 weeks due to a bad stator, but if the stator is bad, wouldnt the quad run like crap? and if its not the stator what could it be??

 

The stator is basically your alternator for your bike. It charges the battery, power for lights, etc. The magnetic pick up is your trigger for ignition. As long as there is enough battery voltage the bike will run and it doesn't need much. Good posibility that all it needs is a stator.