need help with yamaha 250cc moto 4

[tecate87]

1992 yamaha moto 4 250cc, starts runs good. idles fine. when I turn on the lights and try to run, it starts to chug when trying to drive it, shut the lights off no problem.
new battery, always starts with electric starter.
any ideas as to what to look for ?

[ohsobad_chevy]

Are the lights ran off the battery or a stator?

[tecate87]

i believe the stator