The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Crossrodes on April 25, 2014, 09:45:20 PM
-
I have an orange light on the tach on my 79 R65. It is about 1/4" round and is placed near the 8,000 RPM mark. It is always lit...except for today. Today it flashed for awhile and then turned out.
My question is...does anyone know what this indicator is for?
-
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.
-
Thanks Tony. I'm guessing that the light turned out because of a failed bulb or bad connection. But then, I ask myself why is the light always on. I'll have to see if I can find a wiring diagram and see where it picks up the RPM info....I'm guessing it could be inside the tach itself.
-
You lads have just stumbled upon the kernel of a tale regarding a certain forum member known as Rev Light.
Ain't no preacher. He might hear your confession, but it'll pronto be posted here! [smiley=whistling.gif]
-
I got my light to come on just revving the bike in the garage. Seems it started to light faintly around 6k.
-
You lads have just stumbled upon the kernel of a tale regarding a certain forum member known as Rev Light.
Ain't no preacher. He might hear your confession, but it'll pronto be posted here! [smiley=whistling.gif]
Where is Steve so we can wind him up................
Lou
-
Hold on I'll give him shout! :D
-
It could be that you've got a cap or resistor in the tacho which is going out of spec and it is causing the tach to *think* you are spinning faster than you really are.... or maybe it is indicating that you are spinning much slower than you really are... hmmm. Do you have a timing light with tach function? Don't forget to account for the wasted spark..
-
I have a timing light but no tack function. Until now the light was lit at idle so I guess I should take the tach apart and check out the components. If the light is supposed to light when you are over-revving it could also be that the tack is now operating correctly. I'll check it out anyway.
-
I originally bought a couple of these for adjusting our emergency generator at home and the generator at the weekend cabin we used to own.
http://www.ebay.com.au/itm/Spark-Plugs-Engine-Digital-Tach-Hour-Meter-Tachometer-Gauge-Motorcycle-Bike-bLi-/360609870678?pt=AU_Car_Parts_Accessories&hash=item53f605f356
Dirt cheap and accurate.
For what it is worth with a small generator, being closer to 50hz is more important than being bang on 240 volts - 3000rpm is 50 hz.
-
Hurumph!
My 79 R65 never had one. It was not available for very long.
Cheers
Rev Light
-
My 79 doesn't either but I thought they might only have been fitted to R65's.
-
My 'name' is derived from a lack of knowledge of this particular 'rev light' on the tacho. As an owner of a 79 R65 I assumed I knew it all, when obviously I did not. On a similar thread, years ago, I questioned the assertions of someone who was more knowledgeable than myself and subsequently had to eat a large helping of humble pie.
You can never know everything there is to know. Be receptive to new facts when they present themselves.
I adopted the name to remind myself of that fact.
Here endeth the lesson
Rev. Light
-
I also have a 1979 R65. The light illuminates about 6000RPM.
-
Correcting my previous post after a recent ride. I also have a 1979 R65. The light illuminates about 7500_RPM.
-
Don't go into the light, OldGoat!!! It isn't a good thing!
-
I think our '80 R65RS had the"shift light" too...
-
I thought it was the "valve float indicator light" ::)
-
Here is a photo of the 1979 BMW R65 Tachometer. The two wires at the left lead to the over-rev warning LED.
(https://lh5.googleusercontent.com/-j9YQsIfxsws/U5KOZ02YOqI/AAAAAAAAA-M/B9QZKMB3qx4/w913-h685-no/BMW_R65_tach_board.JPG)