[Bubbaj]

I've got 08 sportsman 500 ho efi runs great when lights are off but when I turn lights on it won't idle and runs like crap and when you push throttle all way in it chokes down with lights on and back fires and some days it cranks fine then it clicks like battery is dead but it's not

 

[Kme743]

Have you checked the wiring from the light switch all the way to the lights?

 

[Bubbaj]

No trying to get suggestions of what to do

 

[GaleHawkins]

No trying to get suggestions of what to do

Kme743 has done a great job of doing that. Let us know what you find.

I would start by unplugging each pigtail to each light and test.

 

[RVS Performance]

Check battery connections, solenoid connections, voltage regulator, and stator output.

 

[Bubbaj]

Could a weak or bad battery make it do that

 

[faawrenchbndr]

Do you have a meter that you could put on the battery to check voltage while it is running?