Boxerworks.com

Re: the GEN light...
As answers come, I'll cut and paste them to this first post, so that a quick reference list is developed. Might help someone one day, having it all together.

In your experience, what was the problem when..
the GEN light..

1. glowed slightly, only seen at night.
diode board problem
check brushes for dust and if you have recently changed them, think whether or not the spiral spring is giving enough pressure on the brushes
diode board failed

2. didn't come on at all with ignition on.
a duff rotor

3. turned off at higher rpm than usual?
rotor failed a week later, see #2.
The solution was new brushes

4. didn't turn off when running.
the the 3 wires coming off the Generator to the Diode Board had lost insulation coming out from behind the ignition timing cover and were grounding out

I thought it means a rectifier in the voltage regulator had failed and the alternator was putting out juice but DC was not getting to the battery

Dave R

Back from a long absence

A glowing lamp is most often cause by a failed diode in the diode board but this will not stop the lamp from coming on when the engine isn't running.

If all of the symptoms you mention are present, I would suggest it's one (or more) of the following.

1) Brushes excessively worn and/or sticking in the brush holder... Had this one a couple of weeks ago on the 'RS.

2) The wiring from the bulb to the regulator or from the regulator to the alternator brushes is in some way defective... or the connectors are dirty of loose.

3) The voltage regulator is defective.

Of those, I'd say that No1 is the most likely.

Rob

I don't have any symptoms on my bike at the moment, I'm just trying to collate the collective experience re: the usual causes applied to the usual symptoms. eg, when my GEN light fails to light, it's been a duff rotor. When the light was dimly lit, at higher rpm, it was the diode board...
so, if you noticed your GEN light misbehaving, what was the cause?

For example, what symptoms did these problems cause? How did the GEN light react?

1) Brushes excessively worn and/or sticking in the brush holder... Had this one a couple of weeks ago on the 'RS.

2) The wiring from the bulb to the regulator or from the regulator to the alternator brushes is in some way defective... or the connectors are dirty of loose.

3) The voltage regulator is defective.

Slightly off topic, but what does it mean when the turn signal indicator bulb glows very dimly? This happens occasionally on my bike.

Manfred wrote:Slightly off topic, but what does it mean when the turn signal indicator bulb glows very dimly? This happens occasionally on my bike.

Mine too - on the 1975 R90/6

I've been searching for an answer to this myself.
My experience:

replaced/added diode board grounding wires. no change.

replaced voltage regulator. no change.(though voltmeter does indicate improved charging)

replaced brushes. no change.

traced & cleaned undertank connections. no change.

After much online research I am remain unsure of the cause...

What exactly does your gen light do?

I thought I posted here - but I can't find it. So here goes agin.

For Number 3 in the original post (gen light goes out at higher RPM) - The solution was new brushes.

read all about it: http://boxerworks.com/forum/viewtopic.php?f=1&t=679

SteveD wrote:What exactly does your gen light do?

Apologies for the delay.

Gen light glows very faintly as in waaaaaaaaay less than 1/2 brightness, glow brightens a bit w/ rpm increase to 4k or so at which point it goes dark.

An rpm drop below the "no-glow" threshold results in...a faint glow.
Pretty classic situation based upon my internet research.