Hi

I own a 1984 K100 and it has the classic problem of the faulty speedo....the tachometer works but the speedo stopped approximately two years ago. i was thinking perhaps it was the sensor cable which is attached to the rear drive but the tacho is fine...does the tacho receive a signal from the rear wheel sensor? perhaps its the internals...electrical components such as resistors and transistors? are usually reliable especially for a bike of that age.....opened the speedo ..no corrosion..everything appears to be in good order...any suggestions would be appreciated..

regards'

gabriel

Remove the sensor and clean the surface that goes into the drive. Go over the connectors and use deoxit to clean them and make sure the connectors are actually connecting but checking continuity of each connector and wire with a meter. On an 84 they also had problems with the pins on the rear of the unit where they go into the housing, if you give those a very slight bend to be sure they contact. Inside the unit there some square pins on some of the circuit boards that give trouble, you can give those a slight twist to get them going. Check all the soldered joints inside to be sure they still work and haven't gone open circuit. If you aren't experienced with printed circuit boards then don't try to resolder get a pro to do it.