1982 electrical problem

[bmw38196]

I have a 1982 R100S (used to be a R100RS but had damage to front end when I purchased it) which just stopped running the other day. When I turn on the ignition and run switch I hear a humming sound, the neutral light is on and the tach needle moves up to about 2,000 RPMs. Nothing else will work (lights, starter, turn signals, etc...). I have owned the bike since 1985 with no maintanance problems other then having to replace one ignition coil besides regular maintanance. Bike has 35,000 miles on it. Thanks.

[1505]

If you have a volt meter let us know what the battery voltage is before and after turning on the ignition switch.

Ray

[kioolt]

I'm thinking that you have a loose ground that is common to all of the stuff that is not working. Instead of letting the magnitude of the problems overwhelm you, I would suggest that you treat it as if there was only one problem. I would find out why the headlight is not working and when you find that all of the other problems will be corrected also. Start by putting one lead of a voltmeter on the headlight ground and the other lead of the voltmeter on the negative "post" of the battery. Dol this with the key on. In a perfect world the voltage will be zero. If you have a bad ground than the voltage will be significantly higher. It may even be the total battery voltage depending on how bad the ground is. If you find you have a bad ground by doing this test then you will have to track it down. When you have found it the voltage will be very close to zero when doing this test. I haven't worked on my 82 in a few years but I believe that BMW has always used brown for the ground wire. You problem may be as simple as the ground connection at the battery or on the transmission breather bolt.