nc23 electrical problem (headlights on = misfire)

[willpisme]

Hi, as i said in the title my nc23 has started to seriously misfire with the headlights on full or dipped beam. It runs sweet as a nut with just the sidelights on or with them off.
It seems to run a little better with one of the lights disconnected.
My worst fear is the alternator going but thought i would ask on here in case anyone else had the same sorta thing happen?

Cheers for any advice

Will

[dunkenb]

How olds your battery?

[willpisme]

the battery is about 2 months old

[CMSMJ1]

Aye, does seem like as soon as the lights start to draw then the bike suffers. Got to be worth checking your generator output and reg/rec health too.

I suspect you'll find a knackered genny...

[blueflag]

I have a genny or two if you need one.
First off, check the voltage across the battery terminals when it's running.

[willpisme]

thanks, ill get the multimeter on the battery soon as possible and report back with results

EDIT: If i run the bike with one headlight disconnected it runs completely fine