A Speedometer Question

[Alan Schlosser]

Here's an interesting one. I bought an 83 speedo for my 82 1100L off eBay. Basically, they changed it to 140mph in 83 from the 85mph one thats on the bike. The drive gear and cable part numbers are the same for both years. But, I tried it temporarily hooked up to just the speedo cable and it only runs up to about 35mph, when I know I was doing at least 60. Then I tried it running on a drill motor. Same thing. Plus, it responds very slowly, even when coming back down to zero. Now, most of the wires are for lighting, but there are two wires for the speed sensor. My question is do I need to have these wires all hooked up for this to read properly, or is it strickly a mechanical drive? And if so, what does the speed sensor do for it?
Thanks in advance.
Al

 

[Rocketman]

I'm no tech wiz, but could it possibly be something as simple as a bad cable in the new one? Maybe try squirting some liquid white lube in the new one, or if possible, swap the cable from the old one with the new one, and see if that works?

 

[Steve]

Not sure if it is a "speed" sensor or a "distance" sensor, but that is what determines when the turn signals get turned off. Not necessary for proper operation of the speedometer, but the signals will NOT self-cancel.


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[Alan Schlosser]

I understand the purpose of the speed senor in regards to the self cancelling turn signals. And, it's my original speedo cable.
The next question is: Is the wiring for the speed sensor for the purpose of the self cancelling signal, or is it used for the speedo itself? Interesting.

 

[Alan Schlosser]

I think I found the answer to my own question. The speed sensor is used for telling the self cancelling signals to turn off. It counts distance and speed. It can be tested by using an ohm meter and turning the speedo drive. You should see it make and break. So, I think I just bought a junk speedo.