Electrical gremlins are very difficult to pin down. Based on my past experience, I would suggest checking the grounds as well. I went nuts checking the hot side of the wiring harness only to find my problem went away when I cleaned the ground side of the harness. I am sorry I don't remember off the top of my head where the ground points are on the bike with the exception of the main ground from Transmission to battery. Make sure it is clean and the cable is in good shape as well as the bolt is tight and not stripped.
Oh yes, as far as the positive side of the harness, the starter relay under the gas tank can be a problem area for corrosion. I would check the connections on it as well.
I doubt you need an ignition switch, I have 176000 miles on mine and it is still going strong.
Good luck. St.

Electrical gremlins are very difficult to pin down. Based on my past experience, I would suggest checking the grounds as well. I went nuts checking the hot side of the wiring harness only to find my problem went away when I cleaned the ground side of the harness. I am sorry I don't remember off the top of my head where the ground points are on the bike with the exception of the main ground from Transmission to battery. Make sure it is clean and the cable is in good shape as well as the bolt is tight and not stripped.
Oh yes, as far as the positive side of the harness, the starter relay under the gas tank can be a problem area for corrosion. I would check the connections on it as well.
I doubt you need an ignition switch, I have 176000 miles on mine and it is still going strong.
Good luck. St.

Electrical gremlins are very difficult to pin down. Based on my past experience, I would suggest checking the grounds as well. I went nuts checking the hot side of the wiring harness only to find my problem went away when I cleaned the ground side of the harness. I am sorry I don't remember off the top of my head where the ground points are on the bike with the exception of the main ground from Transmission to battery. Make sure it is clean and the cable is in good shape as well as the bolt is tight and not stripped.
Oh yes, as far as the positive side of the harness, the starter relay under the gas tank can be a problem area for corrosion. I would check the connections on it as well.
I doubt you need an ignition switch, I have 176000 miles on mine and it is still going strong.
Good luck. St.

Gremlins can indeed be hard to find. Some suggestions...

• Be prepared with extra fuses and a test lamp, should the worst happen out on the road. Put those items and any others you can think of in your tool tray now.

• Ignition switches do go bad. Typically it's becasue the switch's plastic base has come loose from the main housing, which lowers the spring pressure on the internal contacts. If you can wiggle that base and get the lights to flicker, then maybe you do need a new switch. BMW no longer sells these, you need to visit: http://motoelekt.com/ignition.htm

• If wiggling the individual wires on the rear of the switch makes lights flicker, then you have a loose contact there, OR corrosion making that contact intermittent. You can gently squeeze the female contact and close it up, then pack it with No-Ox-Id anti-corrosion electrical connection gel before plugging it back together.

• Your bike has the under-tank brake master cylinder, so you need to remove the fuel tank and look at it closely. Caustic brake fluid leaking from the m/c drips right onto the main harness connections, especially at the starter relay on the Left side. Sometimes the 3 voltage regulator contacts on the Right side are also affected. If you detect a gelatinous coating on the wiring there, then everything needs to be washed off with hot soapy water. If your bike has the plug-in mini-cube type starter relay you're really in for it. We can cover that in detail if that's what you discover.

• Both battery cables deserve very close scrutiny. Acid can wick under the cable jacket though the entire length of either cable, but especially the Pos cable going to the starter. If you see any corrosion coming out from under the cable jacket on either cable, then that cable MUST be replaced.

• The two pointy-end German fuses inside the headlamp shell can also loose their connection. Not becasue these fuses are "bad", but becasue they are wholly dependent upon spring tension to make good connections. If you insist on using this type fuse you must insure good tension AND treat each end with No-Ox-Id. Otherwise, convert the fuse holders to the more modern "flat-pack" fuses. Look for an alternative fuse method HERE !

This is not all of the problem areas, but it does cover the main ones I'm aware of.

Good luck.

Thanks for the tips. Gives me a list of things to check which I will do today. Appreciate the help.

OK, checked main cables and they're fine as far as I can tell: no visible acid corrosion, just oxidizing of the copper. Then on to ignition where I cleaned and used De Ox It (tube of No Ox Id is on the way) on all connections (plastic back appears to be fine). At this point, I checked and the gremlin was gone but this has happened before so I proceeded to clean and De Ox It all the electrical connections I could find. (Discovered that PO had installed a Dyna electronic ignition system--only owned bike for two years. Any one need points, condenser, points adjustment tool cheap?). Replaced fuses with blade ones like you recommended. Everything still good . . . so far. Thanks again. We shall see!

Believe I have what you describe as a mini-cube starter relay w/silver cube about an inch square underneath master cylinder. Care to expound?

Thanks for the updates. I never did find a big gremlin in my chase, just lots of little ones. I don't know for sure which one I banished that solved the problem. St.

That's a bit disconcerting from a reoccurrence perspective, especially when on the road. Appreciate your help and support. Fun, fun, fun.

"... Any one need points, condenser, points adjustment tool cheap?)..."

Yes, I'll take those bits. woodnsteel1@gmail.com

Believe I have what you describe as a mini-cube starter relay w/silver cube about an inch square underneath master cylinder. Care to expound?

"Mini-cube relay" photo

If your starter relay looks like the one above, and is a small cube about 1 x 1 x 1", then that's what I call a mini-cube. It should be pointed straight up. You can grab it with your fingers and pull it out of the socket, again straight upward. (Don't worry, it has an asymmetric pin layout that only allows it to be plugged in one way.) Whether you have the metal can (OEM) or a more recent version with plastic cover makes no difference. Either cover can be popped off to reveal the tiny relay, which in my case had succumbed to the brake fluid and was covered in white, fluffy corrosion.

If you look carefully at the schematic on the side of the cover you will see how power flows through the unit.

Schematic on side of starter relay

It won't take too long to see that there are two (2) constantly connected contacts labeled #87, and now that you have the cover off you can plainly see that the 87's are connected together inside the relay. BMW used this relay to take a very shoddy short-cut on Airheads. One of the #87 is connected to the battery Pos (+) terminal. The other #87 is connected to the ignition switch. In other words, if there is any fault with the relay or relay socket, then power problems get taken to the ignition switch, thus the entire bike develops power issues. And your chances of trouble are DOUBLE becasue power has to transfer into and out of BOTH #87 terminals before the ignition or lights will operate correctly. Then, BMW placed this most vulnerable of all relays directly below dripping caustic fluid. :angry:

Recovery steps...
• Wash the relay socket in hot soapy water to remove all the brake fluid residue.
• Use a dental pick to close up the female contacts ever so slightly, if so needed
• Pack the relay socket with No-Ox-Id to stop any further corrosion
• Purchase a new starter relay* and install it

*Luckily this last step is easy. This relay is used in hundreds of applications and made by at least 6 manufacturers. This type automotive relay is known universally as a "Dual 87 Relay" and you can find them on Amazon for about $6. They are available with and without the mounting bracket shown in the second photo. Buy the cheapest relay and if it happens to come with a mounting bracket, then simply saw it off.

The above took me nearly a year to diagnose and discover.

Hope this helps.

Summit Racing - Hella Relay #933791061

RF & all: HD uses that same relay 8187C2 Accel # local dealer will have one

Thank you VERY much for sharing. From their appearance (very oxidized silver) both my regulator and relay appear to be OEM, but untouched by brake fluid, thankfully! New OEM relay is $27! So much for the vaunted German engineering--guess electrics weren't their forte'!

Phil, you are talking about a motorcycle that is now easily 40 years old. I find the Bosch electrics to be more well reasoned than Lucas (British). My first bike was a BSA. I had to teach myself about the oddities of that system. Let's start with positive (+) grounding. And, there is nothing more aggravating than a Jap bike with electrical troubles. I can not speak directly to H-D, or other makes.

Wobbly, or a host of others can and do share knowledgeable insights in to our bikes. That is the beauty of being an Airhead, and the best value of being a member of the Airhead Beemer Club.

I would love to see a pic of your sidecar rig, please...