How does the 2 wire Voltage Regulator function?
 

I have a quick question regarding voltage regulators. Since mine doesn't have one that I can find except under the gas tank by the yoke, which I believe is strictly for the horn (correct me if I'm wrong, please).

All the wiring diagrams I see show to splice it into the yellow off the stator and ground the other wire to the frame. How does this regulate the voltage for anything connected to the yellow wire? Bear with me here on my comparison, but in my mind I see this like having a pipe with water flowing through it, then T'ing off that pipe and putting a valve on the off-shoot, trying to regulate pressure through the main stretch of pipe - it doesn't make sense!

Hopefully this makes some degree of sense and someone can clarify this for me.

It is a zener diode voltage regulator. It cuts off the tops of the positive ac phase and almost all of the negative. Basically it shorts excess voltage to ground. The input resistance would be the coil itself in bike applicaton.

http://www.electronics-tutorials.ws/...e66.gif?81223b

So as long as it ties into the yellow stator wire and grounds to the frame at any point it will in theory function as designed?

Yes. Don't think of it as a water valve regulating the "pressure" of the main pipe, it's a relief valve managing the "spikes" in pressure along the main pipe. Like having an expansion pipe to manage the water-hammer in house pipes, or an expansion tank in a closed-loop water system.

It made sense to me when someone used the term "clipping" of the excess voltage.

If I remember right you have a '01 or close to it? Yes, the voltage regulator is tucked under/inside the frame behind the steering stem back then.

Thanks go to the both of you. The bike should be lit up in no time.

Hi great post and very helpful. my question is does it mean my regulator is knackered if my lights are dim when my bike is ticking over but go very bright and blow when the bike is revved. they used to be ok but I have just fitted a new stator and I am now having problems. I have two wires from the regulator a yellow (going to the stator) and a black (going to ground) Any advice as to sort this would be great thanks.

it's odd that your problem would start after replacing the stator, I would double check that the ground/earth wire from the regulator (and power wire connection) have good contact using emery cloth or sandpaper at the connections. If all is good then yes, a bad regulator will do exactly as you describe. Please post back what you find for a correction to your problem.

so after checking the wiring on the reg and all connectors were clean and made good contact I was getting a voltage reading of over 20 volts when the throttle was opened. I have now replaced the regulator and all is well with voltage readings where they should be at just over 12v