headlight flickered off/on now not working at all

I have a 1978 KZ750. One morning, on my way to work the headlight would go off and then come back on (off/on). All other lights are working fine. I removed the headlight and
had sporadic voltage on the headlight connector. Checked the connections inside the headlignt bracket. They seemed tight. Don't know what to check next. Also the headlight only comes on after I start the bike. The other lights come on when I turn the ignition to on. Anyone go any ideas?

Have you tried it on high and low beam?
Does it make a difference?

How does the high-beam switch feel when you switch it?Can you feel it,"Click" when you switch it?
Might be time to grab a 12volt test-light,and start wiggling some wires around inside the headlight bucket.

And it COULD be a sign that the headlight itself is on it's way out...try a different bulb.

Theres a slick little device called the emergency lighting something or other. If you've got a manual, I'd read up on it before going further. Sorry I don't have more detail.

The device mentioned above functions to have the high beam come on at a reduced voltage to allow you to drive(no bright high beam though)in the case of the low beam failure.

Check the wiring from this box as the connectors get corrosion in them and quit working.

Saki Jockey wrote:

Theres a slick little device called the emergency lighting something or other. If you've got a manual, I'd read up on it before going further. Sorry I don't have more detail.

Um, not on a 78 750 twin there isn't, and a 78 KZ750 can only be a 750 twin

Why does the headlight go on when you start the bike? There's an on/off switch for the lights on the right control pod on the 78 750 twins, they removed the switch but left the hole for it on 79 models.