Alright ive gone through 2 batteries, each new battery will last like a few weeks. I turn the key on and the neutral comes on then i go to start it and it clicks and the light goes off. what could be wrong with this. is it something serious. and when i charge the battery could it still be connected to the wires.
please help.

 

Batteries somewhat recharge themselves during rides. How often do you ride the 400EX? If there are long terms between rides this might be the problem. If you ride often, like a couple times a week. There might be a bigger problem.

 

i dont ride it every week. but i charge it often.

 

If you have a voltmeter...hook it up accross the battery, and start it up. Turn on the headlights, and slowly rev the motor...to about 5000 rpm or so. Whats the voltage read?

 

sounds like you need a stator