Forum bmwbike.com

On my 1953 r25/2 I can't seem to get the red generator light to go out when driving. After further inspection it seems the bottom set of points do not come together close enough to make contact. If I press them together ( while the bike is running) the light goes out. How can I adjust this so it closes by itself? Does this make sense? We tested the voltage coming from the generator and it was 7 volts. And the battery holds a charge when I use a battery charger, but doesn't charge on the bike. Thanks, Trevor

Trevor-
I had a similar problem with my 1952 R25/2 and found the regulator contacts would periodically get corroded and wouldn't make good contact. Cleaning the contacts would restore good service, but I cured the problem by replacing the mechanical regulator with an electronic one. Bob's BMW has them - part no. 12-6030 - at $125.00. That was a couple of years ago. Easy to install and works great.

Hi Trevor,

um andere Probleme auszuschließen, würde ich nochmal die Lichtmaschine testen (Kohlen, Kabel). Bei laufender Maschine und gedrücktem Rückstromschalter - die rote Lampe geht aus - kurz die Batterie abklemmen, dann müsste die Maschine weiter laufen, anderenfalls liefert die Lichtmaschine keinen Strom; hält der Rückstromschalter bei höherer Drehzahl von selbst, könnten die Kontakte etwas nachgebogen werden, hält er nicht, liegt mit Sicherheit ein Defekt im Rückstromschalter vor (saubere Kontakte und Kabel unterstellt), ich würde dann ebenfalls einen elektronischen Regler sehr empfehlen, Preis in Deutschland ca. DM 150.

I bought an electronic regulator from Bobs BMW for my R27 in 1999. It was a square alum tube about an inch long, filled with epoxy into which was set the chip. It had a tab with one hole for a bolt, and places to insert the wires, which would need their stock terminals cut off. I did not want to cut my harness this way, and I was hearing reports of questionable reliability, and that you ever installed your battery in backwards, it would fry the chip.

This electronic regulator cost $100, but I became afraid to use it and sold it for $40.

I had discarded the original regulator before I realized that you could send them to Huggett in exchange toward a remanufactured regulator. So I found a NOS regulator - it must have been one of the last.

Last winter, I removed the battery for service, could not see the terminal markings very well in the dark garage, and installed it backwards for a few minutes. I was thankful to have the mechanical regulator!