Forum bmwbike.com

I have a '37 R12 which seems to have a slowly detoriorating spark strength. At first the spark plugs would last 1000 miles than down to 200 mi now I'm down to only 50 miles before they begin to misfire. The only cure is to replace the plugs. I have tried every heat range and the carb is set in a way that the bike runs great. I know a too rich carb can foul the plugs but the carb setting has not changed since the days when I got over 500 miles between plug changes. Who is the best firm to send the mag to be rebuilt??I guess I'll have to send it out unless anyone has any other suggestions.
Sincerely, All fouled up Peter

Ask around Peter. I had the same problem with an R12 some years ago and a rewind did the trick.

Get in touch with your local vintage M/C clubs and ask who they recommend. Be careful as there are too many people who advertise that they can rewind anything when in fact they can't. It may cost a bit, but it will be worth the expense.

First, you have in fact come up with the correct answer to your problem. Second, you should send it to Andreas and Wolfgang Osterhaus. They are in Iserlohn, Germany and they can take care of your Bosch "D" Zunder (right turn, look for the arrow). I have used them many a time. As far as requiring the coil to be rewound, all you probably need is to re-magnitize the magnets (takes less than 2 seconds) but I will tell you that when they do a rebuild they replace the internal coil at the same time just to make sure. Expect to pay between $600 to $1000. depending on the condition of the generator and regulator which should be looked at at the same time. Any questions write to bmwmuseum@hotmail.com

Gerry,
do you still own your R12?

I had the magneto of my R12 WH completely overhauled by H.Radstaak in the Netherlands. Great job!!
Try Radst038@planet.nl
Good luck!