Originally Posted by Grafspee
Not to hijack things here, but reading this thread got me wondering. Just purchased a 1990 R100GS of unknown history and it ran great for the first 1000 miles that I've had it. Mileage is around 40,000 miles. Now the bike is shutting down on me with no real constancy. I might ride 5 miles, or 25, or 100 miles, and usually it will start back up in 5 to 10 minutes. I just replaced the old cracked coil - no luck, still does it. Looking at cleaning all the electrical contacts next. Who thinks its the Hall sensor, as I am starting to lean in that direction?
Somebody give His Excellence Datchew a call. We might have another potential member of the points cult.
To answer your question, what you describe DOES sound like a hall sensor failure. The only other possibilities are a bad ICU or a faulty connection somewhere. The only sure fire way to check either the ICU or hall sensor are substituting known good units unfortunately. Got a buddy with an airhead? Do these problems only show up after a lengthy warm up?
Try cleaning the battery posts as well as the big ground wire where it attaches to the transmission. That came loose and caused me to die in the middle of the night once. That sucked. Easy fix though. Is your entire bike shutting down, or just the ignition? Do indicator lights and headlight still work when it dies?