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Discussion Starter · #1 ·
I got my bike back after having new tires installed and the speedo has now stopped. As I was almost home, I noticed the needle bouncing around and then pretty much nothing. When I got home, I checked the tire end of the cable and it seems to be on the spinner. Any suggestions for what I may be missing? I probably need a new cable anyway(looks original), but just want to check anything out before I buy a new one.
 

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Disconnect the instrument end of the cable. Spin the front wheel. The end of the cable should turn. If it doesn't, disconnect the wheel end of the cable (good luck on that operation) and see if manually turning one end of the cable makes the other end turn. I don't think it's possible for the speedo drive not to engage the wheel when it's mounted, but worth checking.
 

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Discussion Starter · #3 ·
Well my odometer is still counting the miles as they pass...just no speed reading. so is it prob a bad cable? or do you think i need to rebuild/buy a new speedo unit?
 

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kck3 said:
Well my odometer is still counting the miles as they pass...just no speed reading. so is it prob a bad cable? or do you think i need to rebuild/buy a new speedo unit?
I just spent the past few nights inside a couple of different year 450 speedos. If the odometer is working then the cable is good. The cable is directly to a cup that spins. Inside that cup is another circular piece that is magnetized (or the cup is magnetic). As the cup spins faster it moves the needle that is directly connected to the inner piece. The fast moving outer cup has gears on it that drive the odometer. So, if the speedometer is not moving then something is either keeping the magnetic cups for doing their thing or the shaft that the needle is connected to is broke or jamed.

Either way, you'll have to take it apart to see if it's fixable. It's pretty simple to see how they work once you get it open. If the needle move up but does not return then it's just the return spring that is broke. The same goes with the tach.

What model/yr bike are we talking about?
 

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Here is the best picture I could get of the innerds of one of the speedometers. I think most of the early versions work similarly but there may be some differences in appearance and shape of some of the pieces.

Hopefully this will help clarify the system a little bit. Note that the trip odometer is missing for clarity.
 

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Discussion Starter · #6 ·
Thanks for the info. It is a 1971 CB350. I was hoping it was just the cable because it was working fine until i took it in for tires. When I got home, no speedo.
 
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