Your R65 is secretly phoning home and when it is flashing it is communicating with the mother-ship.
Well actually, on the 1979 model (and as far as i know, only the 1979 model) it was there to let you know that you had over-revved your engine, but during the weekly focus group held at BMW they decided that the crunchy metallic destruction sort of sounds beneath your legs, along with the loss of all power might be sufficient notice so it was deleted from later models.
Sorry, I'll try again and be serious. it was supposed to warn of an over-rev. I've never seen one light up other than briefly on switch on and also as a sure sign that the battery is way too flat to turn over the engine. I have in fact gently snuck well past the red line on my wife's bike to see if it would illuminate, but it never did. Then after i pranged my wife's R65/80 I put the tacho from my 1985 r65 on it. As part of the parts buying project 20 years later to put my r65 back on the road I bought two tachos, one of which has the over-rev light. I am waiting to see if it works or not.
