will start and run only with outside battery scource

[coupracer]

i have a 82 xs400
i can get it started and it runs perfect as long as i have an outside power source attached to the battery as soon as i remove the power source the bike shuts off. i replaced the generator a month ago and it ran amazing up until the a few days ago what could have happened and how to fix it

 

[xs400newbie]

Did you have the battery tested?

 

[coupracer]

brand new when i did the gen.

 

[HoughMade]

But is the battery good and does it hold a charge? New means new, not always good. If a battery is fully discharged even a few times, it may not hold a charge. Also, some batteries are just bad, new. Charge the battery with a trickle charger overnight or a smart charger and ensure it gets to around 13 volts, then test it after it sits for a day to see if it still has over 12.5 volts. If not, your battery is bad.