1981 R100RS Charging Problem. Help?

[khenning]

Oh, and I also pulled out the brush and it's still over 10mm. The book I have says 8mm is when to service so I don't think that's the problem. Also where it touches is nice and shiny.

[SteveD]

I do not get a GEN light at all

Ime...duff rotor. http://www.euromotoelectrics.com/ can replace with new as cheap as anyone. Confirm via testing, then buy the cheap extraction tool. It's an easy job using the correct tool.

[Deleted User 62]

Wow, tons of great responses here. Thanks guys. I do not get a GEN light at all. I took apart the cluster and tested the bulb and it's good so that's not the problem. I'm going to try that penny trick suggested. I also did order a replacement rotor hoping/thinking/assuming that's the problem.

You should really test the rotor before you pull it. The penny test is quick and easy, if the light works. If you have a voltmeter you can test the rotor for continuity while it's in place, but you'll need to lift one of the brushes slightly and put a piece of cardboard between it and the rotor. If it has continuity, it's possible the sheet plastic circuit board you saw in the instrument cluster is not making good contact. +1 on the extraction tool, not any bolt will do.

[enigmaT120]

Did you ever test the voltage regulator? It's way easier to test (and replace if bad) than any of the stuff inside the front cover.

[khenning]

Hey guys. I replaced the rotor and that was the problem. Everything was up and running great until this morning. I went out to the bike to start it. It turned over maybe two times and just went dead. By dead I mean the starter button does nothing. Also, all of my gauges are dead, no lights. So, when the key is in and turned on, I get headlight and running lights, but my gauge cluster has no lights and the starter button does absolutely nothing. I pulled the cluster and noticed my oil light was burned out, which is new. It was working last night. I don't have any spare bulbs so I swapped it with the high beam indicator light and put the cluster back on. No dice. Any suggestions or ideas? I love my r100 but right now it's really kind of frustrating me. Oh, and I checked the fuses, they're fine.

[khenning]

And hi, I'm a horses ass. I bumped the kill switch apparently. Also the gauges were just a loose connection that I tightened up. I feel stupid. But I'm happy too because now I can ride!

[Major Softie]

And hi, I'm a horses ass. I bumped the kill switch apparently. Also the gauges were just a loose connection that I tightened up. I feel stupid. But I'm happy too because now I can ride!

At least you're a horse's ass with a running motorcycle.

Don't worry, we've all done the kill switch thing. After a few horse's ass incidents, one learns to always check that kill switch as the first thing when the starter won't work.

[Deleted User 62]

Not to worry, it could be worse:

[Jean]

Shorting the rings on the rotor ALSO checks the wiring in the whole charging circuit, relieving you of the need to take the instrument cluster apart. You might need a new rotor, but until you do the really cheap simple tests, it might not prove to be the problem. You might need a new VR...
It looks like the brushes are worn a lot, as mentioned by motorhead et al.
The three BIG wires to the diode board appear to show signs of overheating...or is that something dirty? Hope it's just dirt.
You need to get Rick Jones little book on Electrical Troubleshooting, read it, and make a jumper to test the VR.
FINALLY, Rob Frankham write a great short troubleshooting guide back in 2007...May 19, 2007 to be exact. Search the forum and print it, then do it.