bright flickering and dim lights

Is it a regulator that is intended for use with a battery, but the battery is removed? Your description is not surprising. It sounds like the regulator is working kinda OK at low revs but staying switced on 100% of the time at higher revs, shorting out most of the stator output. The regulator might have a fault.

If you get back, is it a single box for the regulator/rectifier or is the regulator bolted to the rear mudguard and a separate rectifier bolted to the frame?


For the speedo, the Vapor is supposed to be able to operate off anywhere from about 6 to 400 volts AC or DC for the external supply. It does not matter which way round the supply leads are connected if on DC.

It is has a coin cell battery inside it that is lets it operate even without an external supply, but when running off it the backlights are dimmer & the warning lights don't work. If the speedo stops working it sounds like this battery is flat. Ther is a little cover on the back of the unit to change the battery. I can chase up the size later if you need it.

If the sppedo then only works when the headlights lights are on the Vapor supply must be connected across the headlight wires. Reconnect them across something with power on it whenever the engine is running. I'd recommend the supply that comes up the the handlebars. If it has an ignition switch that is a good place to pick it up.

Sammo said:

when the lights are on the speedo looks fine, when the lights are off the Speedo back lights flicker like a strobe light.

Click to expand...

It sounds like that when the lights off you have no electrical load to help pull down the stator output voltage. Under no load the regulator spends close to 100% of the time shorting out the stator output to prevent the voltage going too high.

In your case the regulator is not turning on then off every AC cycle as it should, but staying completely 100% on for a period of time across lots of cycles. While it is on 100%, you see no stator output - corresponding to the time the back lights are dark because the Vapor sees no external supply. I suspect the regulator needs something on the DC side to help smooth the voltage but on your bike the battery has been removed. Before changing out the regulator, I would try connecting a capacitor across the DC supply to the bike.

Search the forums - there have been threads before on capacitors in place of a battery. I'd recommend a capacitor of at least 4700 microfarads or bigger at 25VDC or more. You might get away with a 16V one but it might be unreliable. I guess others may have a different opinion.

The capacitor should probably cure the dim / flickering headlight as well by making the regulator behave itself.


There was also a recent thread on how the AC side of your particular single-unit regulator/rectifier unit is connected to the stator. There was info in there that might be helpfull too.