GSX600F wont idle with headlights on

[mattfender666]

Good evening!

I have picked up a gsx600f cheap, it starts and runs well. However i have noticed if i put the headlights on, the bike refuses to idle and will just slowly die.

I have checked plugs for rough idea of mixture and they look good

Have had the carbs off, removed all jets floats etc and rebuilt (all clear)

Have replaced battery with a brand new one, filled and charged.

if i run the multimeter across the battery i get a good 14.8V from the battery at 4k rpm with lights off AND lights on.

Therefore i believe, battery, reg/rec and stator are fine?

Does anyone have any idea what could be causing her not to idle with the lights on??

any help greatly appreciated.

[Bezzer]

You've done all the proper checks to rules most things out,but you shouldn't be getting 14.8v on just tickover. how about the headlamp bulb, last owner hasn't stuck a large wattage one in has he that alternator can't cope with at low revs?
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I used to be indecisive but now I'm not quite so sure.

[mattfender666]

[mattfender666]

Pulled the bulbs to check the wattages, they're 60/55 which is standard, however after cleaning the bulb holders and bulb pins with electrical cleaner the left bulb comes on with low beam and both bulbs light up on high beam?? Does anybody know if this is correct?? If it is then it must have been a short somewhere which was letting both bulbs come on , on low beam?