K Bike Speedo Adjustment
By: Brian Curry
Rob Lentini and I have been having a discussion on the “adjustability” of K bike speedo’s with Rob not being able to find the adjustment potentiometer. I found it and this describes it.
The adjustment pot is on the side away from the stepper coil. It is towards the lights and unless you have separated the speedo from the rest, you will not see it. It is behind the gears that drive the odo, and on the little board that you can see in the unassembled view. This is the board that the 3 pin connector plugs into. This is a high (12V) signal. I think some of it is robbed to drive the electronics for the frequency sensitive circuit that drives the meter that functions as a speedo indicator. Even then it is well buried with the adjustment almost exactly in line with the plastic sheet. This is just like the tach where they obviously don’t want you to get your fingers in there.
Now, how to drive it and adjust it. That is for a later time.
But for those who are adventuresome and have time on your hands, you too can adjust your odo.
Speedo Adjust Pot Details
By Geoff Adams
The speedometer on my ’85 K100RS read about 10% fast at any given speed. It can be adjusted by turning a potentiometer within the speedometer itself.
The pot is the small metal part in the photo just above the yellow plastic gear. Use a miniature screwdriver in the rectangular slot.
An approximate 90 degree turn to the right (clockwise) doubled the error to about 20% high. A turn to the left of about 40-45 degrees (as far as it would go in this case) seems to have exactly corrected the speedometer reading. ( A normal K100RS [2.81 final gear] characteristic is that when in 5th gear, both the speedo and tach needles remain exactly parallel to each other at all speeds.)
The pot is accessible only after separating the speedo from the instrument assembly. There is a single small black screw on the back of the speedo that attaches it to a plastic arm reaching from the center carrier. Remove that screw and the speedo can be moved forward to access the pot. When the instruments are out of the housing, a lot of very fragile pieces are exposed, so handle with care.