The International CBX Owners Association

My tach went looney today right after I started the bike - It' still indicates RPM, but now has a 2 or 3 second "lag" when doing so. If you blip the throttle, it hardly moves at all, but if you hold a steady RPM, it will eventually indicate the correct number. When the engine slows, there's again a 2 or 3 second lag before it shows the correct idle RPM.



I put a new cable on it when I bought the bike a couple thousand miles ago, and the drive gear looked fine when I had the valve cover off a thousand miles or so ago to adjust the chains - I suspect it's something inside the tach itself.



Is this a common problem, and is there any other fix besides changing the instrument??



Thanks,



Don

Don,

Your tach is tanked,that's what they do when they go south.

Anybody got a good used one they'd be willing to part with for something shy of a gazillion dollars??



Don

The tach on my GS850 did the same thing when I bought it last year. The bike had been sitting for a couple of years. After running it for a few days it cured itself. I attributed the problem to a little crud binding the pin that the needle pivots on. If the tach you have is like any other mechanical speedo/tach I have ever taken apart the mechanism is very simple. Just a magnetic disk driven by the cable, spinning inside of a metal cup which drives the needle. The magnetic field of the spinning magnet drags the needle cup with it, thus moving the needle. Not a lot of high tech wizardry in there. The innards of the tach probably just need cleaning. The problem is getting in and sealing it again without having it cosmetically appear like someone went at it with a hammer. Before you throw the tach away and pay a gajillion dollars for another one, try blowing some compressed air into the back of the tach through one of the light bulb holes. If there is corrosion from moisture this may not work and you may have to tear is apart. The crux of what I am saying is that your problem doesn't sound like a high tech one and can probably be remedied with a little effort. Good luck and have fun.



Blaine

Don:



you sent me a private message, can't get to it. I assume you need a tach. I have a couple, but they are all the later version. i.e: 10K is the last number shown. If that is what you need, let me know.

Thanks EMS



Yes, the message was me looking for a tach, but I'd like to have one correct for a '79.



Thanks for the offer!



Don