Tach question

mar

mar

Hero member
Location
California USA
The tach on my 75 Sf spins all the way around almost back to 1000 when hitting the starter . Eventually it settles into the correct position and operates correctly when riding. It is not the original tach and I am not sure what it came off of.
Is there something I need to address before taking it off and sending it out for a rebuild?

Thanks,
Myke
 
I opened up an old CB750 speedo to see how it was constructed.
There are thin rubber 'o' rings between glass and painted cover and also between painted cover and crimp seal on to the base.
 
On the contrary, i have removed my posts. The guy asked my opinion but you know better so lets just let him lever off his old crimp ring and fold it back after. We will not tell him where he can get replacements either as that might upset you as well.
I repair clocks, i thought i was in a position to offer advice but i bow to your greater knowledge. jeeeeeez. :D
 
Mar, post a pic of the tacho and maybe we can help further.
Definitely sounds like something is not right, either in the ratio or the mechanism.
As Paul said, maybe if it was an electronic tacho it would possibly be affected by electrical input.
 
I had one a while ago that did something like this and it was the cable sticking. It would wind itself up and then free off, ping the needle right round and then settle down. Might be worth just slackening of the knurled  ring on the cable at the speedo head and trying it again. ?
 
Thanks for the assistance.
Enclosed is the pic. It is just the standard Larverda mechanical clock. I will see if the cable is routed too closely to the headlight. I know it is a tight fit under there. It might be binding up there until the cable developes enough tension to break loose. I may need to find a little more cable clearance.
In the end, I actually have no intension of opening it up. I am certian nothing good will come out of me taking apart a sealed unit. I do know how to reach out to Marcel.
Again, thanks.
Myke
 

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My two pennorth for what it's worth. Had both clocks refurbed by CB750, the tacho does exactly what the first mail says. Only ever does it on start up then settles down fine, might try loosening off the knurled doo dah see if that helps. Stuart
 
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