Forum bmwbike.com

As a follow up to the polarity thread a few weeks ago, I have installed a new Kleiber electronic regulator on my R27. The generator light behaves properly now, and the generator has maintained its polarity so far.

But now the generator light comes on whenever the headlight switch is turned on, and the generator light will not go off until the headlight switch is turned off.

In other words, the electrical system is perfect when the headlight is off. But turning the headlight switch on and off makes the generator light go on and off.

Any ideas?

Hey Allan,
as said sometimes ago, I don`t believe it`s a regulator fault.
This could only be 2 things:
1: short circuit, anywhere at the headlights
2: generator hasn`t enough power (short-circuit?), what is about your charcoals? the wires are welded or loose?You`ve said that you have a new generator, if it is a used generator, have a look to the guidance of the charcoals especially to the pertinax-plates , they should isolate the charcoals from the body housing, are the tight?not worn out.
I had the problem of depolarising several years ago, i find (after nearly 1/2 year) that the pertinax was grinded(?) away so the + charcoal could(!) get contact to ground and depolarise the generator.
rolf

The generator is new from Huggett. I don't think there is a problem in the new generator or the new electronic voltage regulator, because the generator light behaves perfectly when the headlight switch is off.

So I think your first item must be correct - a short in the headlight circuit that still allows the headlight to shine.

Hey Allan,
my favourite is still the generator, not enough power for headlights, but why?
Greetings
rolf

Please give the Place to Buy the Regulator

Concerning my generator light, I have further observed the interaction of the headlight and the generator light, and I think the problem must be in the Kleiber electronic regulator.

When the headlight is off, the generator light comes on at idle, and goes off when the engine is revved, which is proper. The regulator therefore works perfectly when the headlight is off.

However, when the generator light is on at idle, turning on the headlight prevents the generator light from going out when the engine is revved. To make the generator light go out, I must turn off the headlight and then rev the engine. When the the engine has reached enough rpms to make the generator light go out, then the headlight can be turned on again, and the generator light will stay out until the rpms drop for a stop sign.

So when I am riding in traffic with the headlight on, the generator light comes on at every stop sign. To make the generator light go out, I wait until I am moving again, then I turn the headlight off, which makes the generator light go out. Then I can turn the headlight back on and the generator light will stay off.

Here is another test that really shows the problem:
Riding at 60 mph with headlight on.
Pull in the clutch at let rpms fall to idle.
Generator light comes on as it should.
Release clutch and let rpms return to 60 mph.
Generator light stays on (this is the problem).
So then:
Turn headlight switch off, generator light goes off.
Turn headlight switch back on, generator light stays off, which is good.

Therefore I think the "brain" in the electronic regulator is faulty!

Allan,

A faulty behaviour of your battery could explain a lot.

Just to exclude a fault in the battery, install a battery of one of your other BMW's. Minus to frame ! If all would become normal install the mechanical Z-regulator again.

Han Verhagen

The problem was that the generator light was activated by turning the headlight on at idle. The only way to make the generator light go off, was to turn the headlight off. Or, to use the headlight again, increase the revs, turn the headlight off, and then turn it on again.

I spent all yesterday at Guenther Wuest's shop, working on the bike under his direction. We ran the motor using gas from a plastic bottle. At the end of the day, the electrical system worked, but he does not know why.

I took three regulators: the Kleiber electronic regulator, a new mechanical regulator that Guenther had opened and cleaned a year ago, and a new sealed mechanical regulator. We tried all three regulators and repolarized with each change of regulator.

The pole housing and rotor are recently new from Huggett. We did find that one carbon brush had a broken wire, and we replaced that brush. I was hoping that would solve the problem, but it did not.

We removed and tested the magnets, and the rotor. We even put an R25 rotor in the generator.

My battery was recently new, but we also tried a second battery.

All day, the generator light acted strangely, and the readings on Guenther's voltmeter and ammeter were strange. He thought the generator was making alternating current.

Late in the day, we were about to give up. Guenther said to put in the opened mechanical regulator for the second time, without its cover, and also put in my battery, and my rotor. He cleaned the regulator contacts, and I polarised it again.

This time the generator light worked, even with the headlight, so we put the bike back together. He took his R60 and I took the R27 and we went for a ride. Today I rode the R27 some more, and it is still OK.

I have no faith that it will remain OK, and plan to install a horn switch between regulator terminals D+ 61 and B+ 30/51, so that I can repolarize by pushing a button.

Guenther has a theory that a diode needs to be added on one of the generator terminals, to help the regulator reset itself properly. Maybe I will go back to him for that.

Allan,

Do not add an auxillary switch for the purpose of polarizing the magnetic field of the stator of the DC generator. Nobody of the Dutch BMW Mono Club (of which I am a member) needs to do that.

In the previous thread you mentioned that your colleague had the impression the generator signals had an AC component. This might very well be caused by floating brushes. It explains :
1) The red charging lamp when you switch on the headlamp (too high internal generator resistance)
2) The occasional depolarization of the generator. The reason is that at full voltage the DF side of the field coil is connected to the + of the battery via the voltage contacts of the Z regulator. A short voltage drop on the + brush (due to a mechanical brush jump) makes the field current reverse its direction and depolarizes the stator field.

What to do :

1) Check wether the collector is not too far out of round. I think 0.1 mm is a maximum. 0.04 mm is the official BMW figure.
2) Check the pression of the brush springs. 300 400 gram is the right value. It is much more than you are used to with one of your twins.

Good luck
Han Verhagen

The generator light stayed off for 2 days and 100 miles, until I turned the headlight on one evening and then let the revs drop to idle. That made the generator light come on and pulse, indicating that polarity was again lost.

I was just at the point of installing the polarization switch when I read your message.

My rotor should be round, as it is a new Huggett rotor. One of the brushes had a broken wire and in replacing that brush , we did notice that one spring was weaker than the other. We wound that spring some more to make it tighter, but I am going to order two new proper R27 brushes, and will check the roundness of the rotor when I install the brushes.