The headlight is a fairly simple setup. You have 3 wires Green,Blue and White. Green is ground, white is high beam and blue is low beam. The blue and white are switched in the left handle bar switch and the green is either connected to the wiring harmess or on the headlight mounting bolt. With your symptoms either you have a bad ground or a switch problem where it is making intermittent connection.
Vintage racing - old guys on old bikes
Thanks Ill check that out. What about the bulb or a fuse? Could that be an issue as well?
Check the fuse, if it looks a little brown then it is about to go (if it was the fuse however all the lights would be giving you a problem, not just the headlight). For good measure I would clean the fuse contacts anyway (small wire brush).
That should be a sealed beam bulb on your honda, if it is about to go you'll see some slight condensation inside the headlight. See if you can see if the filament is loose. Usually if a bulb is bad, tapping on it with your fingers will case it to flicker.
In this case I'd say clean the headlight contacts (both male and female) and also clean the bar switch with the high beam swith in it (I think it is the left). Trace the wires and check all the contacts (a loose wire is probably your culprit).
If all this doesn't work come over and I'll go over it with you.