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I've just finished rebuilding a R51/3 (1954) It starts and runs just fine, except the generator light doesn't go out. My carbon brushes and springs are new, and don't stick in the holders. I've take the armature and stator in to a generator shop, and the armature is fine, the stator is shot. I bought the 4 new stator field windings and replaced them in. When I put it all back on the bike and started it up, The red light was still on and I could hear the armature rubbing a bit on one of the field windings. I took it apart again, and adjusted the winding (tightened it up to pull it back) and the light is still on. With a cheap voltmeter, the generator give off about 3 volts idling and 4 volts revved up. I think it should be over 6, maybe 7.

Any advise someone could pass down? or details I should check? Thanks!!

Hello, I`m having the same trouble on my R26....try replacing the voltage regulator. Yours may no be any good

Hallo Stacey,
you have replaced the Stator field windings, have you replaced them in the right direction(?) you know NORTH-SOUTH-NORTH-SOUTH?
Is the polarity of the generator right?Try this first :span B+ and D+ for 1-2 seconds to polarize the generator.
Greetings
rolf

Hi Rolf, Thanks for the info.

I did put the stator field windings in the correct order (north, south, north, south) I don't think the polarity of the generator was correct, as I didn't have any magnetism. So I did polarize the generator by connecting the positive of the battery (B+) to the wire that connects to the carbon brush, out of the field windings (D+) I am now getting magnitism, but the generator light is still on bright. I still get about 1volt out of the D+ at idle and about 2 volts with the throttle really revved.

My voltage regulator is the brand new electronic type.

Do you have any other suggestions? thanks!!

Hallo Stacey,
if the polarisation was not right, it was always the same magnetism, equal what direction the current flows.
How much is the resistance (Ohm) of the windings? I must read again how much they had to have and write you tomorrow the value (it must be something about 5-10 Ohm).
There is 1 winding with an extra resistance which should not be connected with the electronic type!!
First: measure the resistance of the winding( all wires disconnected).
If this is ok, measure the outgoing voltage (without regulator) it shoul rise up to 40-60 Volt. If it does, there is something wrong with your electronic regulator or( more probably) with your connection between regulator and the othe electric. that we could check after you have done the measurement.
Greetings
rolf

Stacey,

At Johns beemer garage there is a Butler & Smith service bulletin on checking the generator. It's a Pdf file so you'll need Acrobat to read it.

http://www.beemergarage.com/documents/genadj.pdf

Ben

Thanks for all your help Rolf,

Your last comment about the regulator not hooked up correct was true... It is usually the simplest things.I didn't add a wire to the number 31 post in the regulator and hook that up to the ground in the generator body. It stated in the instructions that you wouldn't need to if the regulator body was in contact with the generator body. Maybe I wasn't getting enough ground contact on the bottom. Anyway the light is out.... Hurray!

You could have a bad battery. Checking the charging system takes a
few steps.
If the commutator is black, lightly clean it with crocus cloth or
fine wet or dry sandpaper. Go easy, you could get it out of round.
Battery, loose connections,brushes and dirty commutator are the usual
suspects. Beyond these, follow this: check each adjacent segment of
the commutator,they should measure about .1 ohm. Measure between each
segment and the iron core, this should be infinity. Measure between
the field windings, between D+ and F should be 2.5-4 ohms. Now you go
to some real voltage measurements. Using a digital voltmeter, No-load
voltage check:Disconnect the battery and switch off all lights etc.
Connect a meter between 61 and ground. Start the engine and rev it
until the voltager stops rising. Should be 7.2 to 7.9 volts.Now
switch on the light and press on the brakeswitch, Voltage between
51/30 and ground should be 6.5-7.4 volts. Circuit breaker cut in
voltage:Connect the battery, connect a voltmeter between 61 and
ground. Now disconnect the lead from 51/30 and connect an ammeter
between the terminal and the lead you just disconnected.Slowly rev
the motor from idle until you see the ammeter take a jump. The
voltage meter should read 6.4-7.1 volts. Reverse current to close
circuit breaker test: Use the same setup as before, but the ammeter
must be able to measure negative currents or you will have to reverse
the leads. Rev the motor until the circuit breaker closes, now slowly
drop the revs. The current from the battery to the generator will
rise to 2.5-9.0 amps, then dropping suddenly to 0, indicating the
circiut breaker has opened. This test your generator and regulator.
If you flunk any of these tests, you will need repairs. Good luck.
Brian Caro

I might mention here that the light could be on due to a short or reversed polarity, which is very common after working on the generator, especially if stray currents booger up the residual magnetism in the windings.! In my previous comments, I am assuming that the system is connected properly.

hey Stacey,
congratulations.
But to make the thing complete : THE WINDINGS HAS A RESISTANCE OF 3-4 OHM, THE WINDING FOR THE REGULATOR 6-7 OHM.
GREETINGS
ROLF