Hello all,
I recently got a hold of a 1985 BMW k100rt that had a small fire. Picked it up promptly after the insurance company cleared it. Most of the damage was cosmetic. The fire had melted the throttle side handle bar assembly, fuel pump, and some of the plastic parts of the inner fearing. I bought a used assembly for the ignition right turn signal and cancel switch and thought everything would work out. Got it put back together today and looking pretty and neither of the turn indicator switches would work, started up just fine so I know that the whole assembly wasn't the problem and the fact that the left side assembly was unharmed by the fire. I read elsewhere that the problem could be a fuse that work the turn indicators and the horn, but the horn works just fine. I took it for a spin to find any other problems and after about 5-10 miles of riding the gear indicator went from 5th gear to first, I pulled over and started it again and the same thing. It reads 1st in 1st gear, 0 and neutral in 2nd, 1st in 3rd, 0 and neutral in 4th, and 1st in 5th. Then after some more riding it would sometimes flash from 1st to 8th when changing from 3rd to 4th gear. Not sure where to start with any of these problems. Thanks in advance for any advice!

Passion85

Both left and right side handle bar flasher controls (brown wire) are fed from the turn signal cancel switch.
Or the wire (brown/white) is burnt/cut, or you have a problem with the flasher unit (Green module in the electrical tray under the tank)

The strange gear indications sounds like the transmission gear indicator switch at the back of the transmission is acting up.  The way you describe the display, I'd say contacts in the switch are corroded and not making contact.  It needs to be removed, cleaned and reinstalled.  This requires the swing arm to be removed, which is not a small job.

Is there a step I can try for the gear indicator before tearing the whole rear end of the bike of? And thanks crazy frog I'll check those things hopefully just some burnt wires. Does that green module control anything else or only the turn indicators?

Passion85 wrote:Is there a step I can try for the gear indicator before tearing the whole rear end of the bike of?

Disconnect the connector underneath the RHS battery cover, and short the wires
at the harness side in the config related to each gir as shown in the link.

http://www.ibmwr.org/ktech/trans-switch.shtml

You could try this little dodge, it worked for me.

https://www.k100-forum.com/t6936-gear-position-switch

Paul.