Kate has had some good luck asking a question into the wind, so I thought I’d try it here to see what happens.
My big, black, and greasy 1977 BMW R100/7 sidecar rig won’t start. Turning the headlight switch all the way on results in a high-pitched whining noise from the headlight relay located on the right side of the headlight bucket pictured above; turning the turn signals on SOMETIMES results in a lower-pitched buzzing noise from the turn-signal realay in the left side.
Clicking on the picture above will take you to this Flickr photo page, which is annotated with notes and the steps I can take to reproduce the problem. Anyone reading this that could help, do you think you could follow the link, read the steps, and leave a comment with any helpful advice?
I’m hoping to prepare a lean, mean, hierarchical list of things to do when I get out there next time. Any suggestions, O Internet? I should mention that I have a multitester and know how to use it (kind of), but my grasp of “check connection” is pretty much limited to “wiggle the wire and see if it makes crunchy noises.” Any tips about how to check if a wire is doing its job?
Kieran, do you know any Buckaroo Banzai types at MIT that could help?
tikaro.com 
2 responses to “Help, O Internet!”
Hi
I own a 1976 R90/6 which has developed a similar problem to the one you have described (relay buzzing and other weirdness). I am very confused when it comes to wiring. Can you tell me if the relay buzzing was just a symptom of another problem or was it actually the problem? My bike has a voltmeter which is registering a discharge anytime the headlight, blinkers or brake lights are turned on. The buzzing only happens when the headlight is switched on (but it has stopped working). The blinkers and brake light still work, don’t make the buzz, but cause the discharge to register on the voltmeter.
Hope to hear your advice.
Lynne.
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Hi Lynne! It turned out it was dirty contacts on the big relay under the tank. Try taking off the tank, pulling out all the square relays that can be pulled out, then scrubbing the contacts with a toothbrush. If your problem is the exact same as mine, that’ll fix it! 🙂
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