I always thought that when you pressed the starter button, it killed the lights. So they (the lights) come on with the key, go off whilst you're actively trying to start the motor, and then come on again when you release the button. Is that true or is it just the way it looks because the starter is pulling so much power than the bulbs don't stay on?
I'm sure I've read on here that if the fuse for the lights is blown, you can't start the bike. So there must be some kind of connection between the lights and the starter circuit.