Completely stumped with my tach

[11davie]

My tach has not worked for 15 years or so. Tried to fix it over 10 years ago and had no luck, and it's been long enough that I don't recall all I did the first time, but I know I bought a used instrument cluster to try and that did not fix it. I just tried​ tackling it again without any luck. I tested continuity from the grey wire on the right coil all the way to the tach connecter of the wiring harness, and from the connecter on the tach to the screw on the back of the tach and it was all good, about an ohm of resistance. From what I understand is that the grey wire sends a pulse to the tack. Knowing this I used my voltmeter on the AC setting, and while running a can measure a changing voltage with engine speed at the connector. Don't know what to try next.  Anyone have an idea? Is there a way to test the tach?

Levin

[Walt_M.]

My tach quit working about 32 years ago. I took it apart and found a broken wire in the armature. Somehow I was able to solder it and it has been working ever since.

[11davie]

Thanks Walt, I should have thought of that while I had it out. I will check that while I still have the fairing off. I'm curious if there is a way to test the tach with a battery/DC voltage. Think I'll do some googling.

[11davie]

So I was in the garage working on something else, and noticed the dwel/voltage/tachometer meter left over from the days when my cars had points. I can probably use this to check that the tach is at least getting a signal. Hopefully I can get to that today.

[11davie]

It must be something in the tach. I was able to get an rpm reading with my dwell meter at the screw on the back of the instrument cluster. I removed the tach and looked it over but could  not find anything, at least that I can see. It even looked like the tiny windings at the needle would move when I rotated the needle.  Also checked for obvious bad caps. I think all I can do now is look for a working used one.

[11davie]

Well, still stumped. I've tested + voltage and ground to the cluster. Bought a cluster in great condition from ebay with high hopes, but it does not work either. Wish I knew someone with a Vision so I could test out my two meters I have now! My next idea is to run a new positive straight from the battery, new ground and new tap to the coil and see if that gets me anywhere.

[fret not]

At this point I would try to contact Tiger for any insight he might have in this area.  Somewhere in my imagination I seem to recall a comment about a situation like this that points to the TCI box.  I am not an electrician or electronics sort of guy, and depend on others that know more about such things, or schematics for sorting such issues.  I wish you good luck finding the answer.

[Walt_M.]

OK, I did some research on this as I have a wiring diagram and a spare instrument cluster. The tach needs negative 12V on the black wire and positive 12V on the brown wire. You will then have positive 12V on the gray wire from the tach. The ignition grounds this gray wire 100 times per second to read 600 rpm. I tried to do this manually but I can't move that fast. I may be wrong but if you put positive on the brown and negative on the black and you have positive on the gray the tach should work.

[11davie]

Thank you Walt! I did not catch the neg 12, I was looking at the wiring diagram in the tech section. I do have a service manual at home, I'll check that too and also do some more voltage check.

Fret Nut, I did see that there is a TCI connection, so that is another item for me to check out too. More garage time...

[Andrew]

Did you get the tach figured out? Mine isn't working either. Haven't tested anything yet, but prior knowledge is key

[11davie]

I have not dug back into the tach since my last post. Still on the to do list. This is off topic but I just spent many hours trying to save myself $60 by changing the front and rear tires myself. First time ever doing that and quite possibly my last. I had no idea what a bear that can be! The worst part was getting the front to seat, I even gave up at one point and took it to a shop to pay them to do it, and they couldn't get it to seat either. I did finally succeed by leaving it in the sun a 90 degree day and  using a racheting tie down. That wasted so much time that the tach most likely will not be worked on for a while.

[Walt_M.]

Too bad you had so much trouble with your tire change. I have been doing it for a long time but I still remember giving up on my first one. A hint, I use 3 high quality tire tools and make sure the tires are nice and warm. You already know about the ratcheting strap for seating the bead.

[fret not]

Like so many things, if you know how to do it, it's fairly easy.  I have heard some folks say that if it is hard to do, your technique is wrong.  Changing tires is not something I do often but over the years I have changed quite a few, so I have a relative familiarity with the process.  The tire bead must be down in the center of the rim on the opposite side of the wheel that you are levering.  That and a bit of lube should make the job a bit easier, though some tires have a very stiff carcass, which can cause a few expletives to be offered.   

If you can watch someone do a job they are very familiar with they make it look easy. 

[QBS]

Some tire mfgers. put a red dot on the side wall that marks the heaviest area of the tire.  This done so that when the tire is installed on the rim the installer will know to place that spot 180 degrees away from the air filler on the rim and thereby offset the weight of the air filler.  This will alieviate the need for some of the balancing weight to balance the tire wheel assembly.  The same process applies to auto tires.

[Kenny]

     Seeing you folks are talking tires :
         Probably 10 years ago I mentioned that I was going to try using Balancing Beads in my motorcycle tires , Anyways I thought I should report back on them. They work great and I never worry about balance weights or paying someone else to do the job.  Line up the yellow mark on the tire with the valve stem and seat the tire on the rim then, With the valve stem removed  use an electric vibrating pen to install the balls in the tire. Aprox. one ounce in the front or back.
                        Cheers Ken S

[11davie]

Honestly, I probably would tackle it again in a few years when it's time. I also did go through the trouble of finding the heavy side of the wheel and aligning it with the light end of the tire. Interestingly the heavy spot was about 6 inches or so away from the air inlet aligned with a "spoke".  Also added balancing beads, but too early to tell how well they work other then on the two short rides I have been on I didn't notice any issues. I found this site very helpful. http://www.clarity.net/adam/tire-changing-doc.html

As far as the tach goes, I might look at it again in a few weeks.

[Rikugun]

The tach issue definitely has my interest so I'll be keeping an eye on this thread.

Kenny, thanks for the tire bead update. I remember being a bit skeptical when that post came up years back so it's good to know the product works.