Hiya!
Will run fine with the sidelights on, with headlights on if stopped at - say a roundabout, the engine will flutter then die - if the starter is pressed the engine will spin but fail to catch until the lights are switched off?
The only thing I can think that is different is one of the headlight bulbs is a H4 55/60w car type instead of the standard H1 Jap 30/60w bulb? The LBS didnt have any H1 bulbs and like me - had never even seen one! They could get one in but it would cost £12.57... I elected for getting a H4 and breaking the two lower tabs off...

Personally I wouldnt have thought the extra 25w wouldnt have made that much difference? I may try pulling the plug off of one bulb and seeing if that makes a difference? (obvoiusly just around town...)

Battery & starting are fine otherwise, just the stalling prob when stopping? Tickover is set slightly high at 1500rpm...

Any ideas?

i never start my bike with any lights on. i also switch the lights off before i switch the engine off. and i use the key to switch the engine off i NEVER use the kill switch!
yes some bulbs pull too much voltage and the engine doesn't have enough juice to start.
but once my bike was running, having the headlights on didnt affect the idle speed.

SORTED!
Tried swapping the new bulb with a standard 30/60 from my mates CBR - to find that whoever packed the bulb in China had put a 80/100w bulb in a 55/60w packet...

The bike is clearly not happy to run such a load in tickover....

i used to have 2 X 80/100W* bulbs (now have ballast HIDs) and bike idled just fine. could not start the bike with the lights on though.

* you MUST fit the relay mods before you fit these or you will melt your switch gear!