Tach. Problem

[Firehawk068]

I've been having this issue with my tachometer for some time now..........
When I first start the bike up, the tach does not work for a few minutes of riding..............then after a few miles......voom, it magically works.
It does this whether it's cold or hot? 
Seems to be worse if the bike has been sitting overnight.
Any thoughts?
Has anyone else had this issue?

[carsick]

Have you hit it? Mine needs to be cuffed right on the top of the cluster every time I cold start before it reads anything. Not very high tech but it works. The PO's crash might have influenced this.

[RichBaker]

I had the same problem last summer.... but only when it was over ~100F. I swapped out the cluster with a used one I had(swapped speedos, so I had correct mileage) and I haven't had the problem. Don't know if it was the tach or the cluster, though....

[mijohnso]

My 1986 has this same issue, except today, it didn't work even after an hour long ride. Quite frustrating. If I gain any insight into what the problem is, I'll let you know

[Firehawk068]

Since I had to recently pull my cluster to fix my fuel gauge that came apart, I looked into the situation with my tach........
Seems to have been some sticky residue of some sort on the rest pin for the tach needle(don't have a clue what it could have been, or how it got there)  :scratch_one-s_head:The needle would stick to it if the bike sat for a couple hours or more.....
A little rubbing alcohol on the pin, and no more stick......The tach works perfectly now.
I also squirted some 3-in-1 oil into a turned upside down speedometer, and worked it in......then squirted some more and let it sit for a couple days upside down......
After putting the cluster back on the bike, the speedometer no longer howls..........

[FJmonkey]

the speedometer no longer howls.

If some lube fixed the howl...then it will return....start looking for a new speedo or a shop that will rebuild it. The bushings are worn and will return to the squeaking wheel (more lube next time will not last as long). Depending on how much you ride it may take years before you need to lube it again (try thicker lube). rest assured, it will tell you when it needs more. Good luck.

[Firehawk068]

Yeah, I figured that it would eventually get noisy again......this will buy me some time.
I already have a spare cluster if i need the gauges......and I checked with a local well-known shop that rebuilds gauges "Dick's Speed-O-Tach" in Tempe, and the guy that answered the phone says to me. " Oh.....they don't make parts for those anymore.....there's nothing I could do with it" I thought to myself........Really..........did a guy that rebuilds vintage speedometers really just say that to me?
Anyway, I have a Zumo 550 GPS that I am installing on the bike.........so I don't really need the speedometer, but the mile counter would be nice to keep, for service intervals and such.

[FJmonkey]

The mile counter will keep clicking the miles even with the speedo singing like a strangled cat. It is driven by a mechanical worm drive from the rotation of the cable on the back side of gauge. The speedo is driven by magnets. When you spin rare earth magnets surrounded by rare earth magnets the attraction gets stronger as the spin increases. A coil spring is pushing the needle to zero but the spinning magnets push it away from zero. The faster the spin the further the needle moves. That is my understanding of how many speedos work. If I am wrong then another with chime in to correct me. Either way your odometer will keep on clicking the miles for you.