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Hi all, I have anew to me 1971 r50/5 with a 75/6 engine.. the PO has already swapped the headlight to an h4 r65 headlight.. the other day the headlight died... I replaced the build with a new h4 bulb and that one worked for two minutes... I assumed the fact it died was the lack of relays.. so step one I took apart left switch and clean contacts and greased switch with dialectic grease... so now I'm on to the relay and I am trying to figure out how to wire it up.. does anyone have a wiring diagram on how to do this? Thanks all

What relay do you have?

Kurt in S.A.

These are a no-brainer. Use a fraction of the output and way brighter.

http://www.cyclopsadventuresports.com/l ... bulbs.html

I bought 2 30 AMP Bosch SPST RELAYS

I bought 2 30 AMP Bosch SPST RELAYS

The new H4 bulb blowing almost immediately is a worry, and is not likely to be caused by lack of relays. Did that happen after you started the engine? If so, it is likely that there is a problem with the voltage regulator failing to limit voltage to a safe level. I would test the voltage at the battery with the engine off and then with the engine running and at revs above idle where the red alternator light goes out. If the voltage goes over 14+ volts there's your problem and a new solid state VR would be the solution.

Relays are a good way to protect the switch contacts and supply more volts to the headlight.
Here's a suggested layout for the /5:



Best of luck getting it sorted.

Edit: If you are having difficulty reading the numbers on that diagram send me an email and I'll send a bigger PDF image.

Thanks Airbear! Great info. Actually I never actually had the chance to start the bike. I noticed the headlight was out on the last ride. I then changed to new bulb and turned the key to check that it was working. I turned off the ignition and turned back on and the light went dead.. the marker light goes on and I now the high beam indicator light stays on all the time

Are you sure the bulb is actually blown by looking carefully at the filaments. In any case it wouldn't be both Hi and low beam blown at once.

Could it just be a bad connection or a faulty switch.

If the bulb really is blown then short of it being a dude the Voltage Regulator is the only other possible cause. If I had to guess though I'd say that is not the VR as you would have other bulbs blowing as well like the tail lamp. You could look at the tail lamp bulb for a clue as if it's been seeing high voltage it will be blackened inside.