tach question

[fishntxflats]

Help Please!
  New owner of 1982 r65ls the tach needle bounces, all of the "idiot lights" oil...gen..neutral...etc work but the rpm's don't...any recommendations, or answers would be greatly appreciated, very respectfully, a new friend, DB

[Justin B.]

Well, Dan, you might want to clean the contacts inside the plug that plugs into the tach assembly and the mating pins up inside the tach housing.  These things are known for plug-together electrical connections getting a bit crusty with age.

But, you say the tach "doesn't work" and also that "the tach needle bounces".  Which is it?

Welcome aboard, seems the percentage of LS bikes is rising quicker than the standard ones!

[fishntxflats]

Wow that was fast, Thank you, I will try that asap and let you know if it worked.  The needle just bounces 0 to about 1000 rpms start up, then after about 5 min of riding 0 to 500 maybe.    It's a clean bike repainted black used to be red.) needs brakes but I have those in the mail to me.  I absolutely love BMW though, it has been better than all of my US or Japanese bikes.... Thank you again!

[Bob_Roller]

The electrical signal for the tachometer comes from pin 7 of the ignition control  unit (ICU) under the fuel tank. I don't know your mechanical experience, but you may want to check this wire from the ICU to the tachometer connection for security and cleanliness. Also there have been problems with solder connections on the printed circuit board inside of the tachometer.

[Justin B.]

It's not real hard to make it red again!