Topic: CB750 Tachometer / rev counter repair

[jebon]

Hi.
In May this year my tachometer suddenly stopped working (cable is turning).
I don't want to bash 750faces.com but it's already been in Holland and after 4 months and aprox. $200 it came back still not working.
Reply on messages is really slow so I thought I'd ask in here.

Any idea what could be wrong with it and if this is something I can fix myself?

[robvangulik]

Did you check that the cable and drive gear on the camshaft function as they should?
Have you tried to drive the tacho with a powerdrill?

[jebon]

Did you check that the cable and drive gear on the camshaft function as they should?
Have you tried to drive the tacho with a powerdrill?

Yes, the cable is turning and has resistance. I also tried a square nail in a power drill. And actually that made me worry a little if I have spun it too fast and that could have broken it again.

[Flyin900]

I know the speedo runs reverse when using a drill to test the operation. Not sure about the tach, yet when the motor is running you can check the rotation direction of the cable drive and also confirm the tack drive is functional.

Regarding CB750 gauge repair my understanding is Marcel does not repair anything, he only does cosmetic fixes and cleans and lubes the mechanism internally.

There are US companies that do gauge repair too. I used a fellow in Georgia for a rebuild of my CL77 speedometer earlier this year. He didn’t do any cosmetics, just internal work on the mechanical stuff. He wasn’t cheap either at around $225 US. He was quick though with less than two weeks turnaround time.

Here is his information Joseph Levine: https://joellevinecompany.com/speedo-tach-repair/

[RAFster122s]

Hi.
In May this year my tachometer suddenly stopped working (cable is turning).
I don't want to bash 750faces.com but it's already been in Holland and after 4 months and aprox. $200 it came back still not working.
Reply on messages is really slow so I thought I'd ask in here.

Any idea what could be wrong with it and if this is something I can fix myself?

My understanding is Marcel only cleans and does cosmetic rebuilds of speedos and tachs.
There are several places that do repairs. Sunnyvale Speedo being one I used years ago on a automotive cluster…

[Geoff Hastings]

The tacho internally is not gear driven but driven by a spinning magnet so running it in reverse shouldn’t do any harm. Try running it both directions with your drill, I’ve just fixed my sons CB 550 tacho and it was the rivets holding the magnet assembly that were slightly loose. If I put pressure to one side of the cable where it connects to the unit  while the engine was running the tacho would function but as soon as I released it the tacho would stop.
If you do strip it down don’t go mad lubricating it, just a few tiny spots on the bearing surfaces.