Weird Tach Behaviour

[Anonymous]

Has anyone come across this, if so what does it mean.
When I am riding the Tach behaves normally until the rev's rise above 5000RPM at this point the needle starts going backwards even though the engine rev's are still rising :?
Its an old GS1150 '84 and I'm pretty sure someones done a dodgy job on the electrics

[Robert Corrie]

My 84 1150ES does the same thing. If you get it figured out PLEASE let me know. Robert

[moto_dan]

My 84 1150ES does the same thing. If you get it figured out PLEASE let me know. Robert

I ride a '83 GS750es and my tach has the same symptoms. Must have something to do with the electronic tachs as opposed to the earlier mechanical ones, so if anyone knows a fix I'd like to know.

[kz]

This topic has been discussed before and my solution at that time was to change the tacho, because I was lucky to found a used one to reasonable price.

Now my "new" tacho starts to behave the same way.

I suspected the two condensator?s on the tacho circuit board and have bought to new ones and replaced the condensators on the "old" tacho and remounted it on the bike.

This evening I only had the possibility to check it up to 8000 rpm, but so far so good.

I will check tomorrow and let you know if I found the error.

The condensator?s costs only approx. 25 US cents each so I hope this is the reason.

[Anonymous]

tach troubles

I have an 83' GS 650 L and my tach does the same thing, very iritating.

fear not you are not alone, and i look forward to the results of the testing.

[kz]

Now I have tested the tacho, but I am not complete satisfied.

From the start the tacho bounced at approx. 5000 rpm and upwards and the needle never came higher than 7000 - 8000 rpm.

After changing the two condensators the bouncing has stopped and the needle goes all the way up to 9000 rpm, the needle never goes backwards any more then it not should.

However I still have one error and that is that the needle "hangs" for a very short period at 7500 - 8500 rpm and then suddenly goes up to the actual revs.

I don?t know if I really found that?s wrong, but the tacho is now usable and I think this is a second problem and related to the mechanics in the gauge (or something else).

The condensators have stock number 67-013-38 and 64-013-46 at http://www.elfa.se/en and click the button "Datasheets", where you can find a PDF-sheet and buy them at any local dealer for a dollar or two.

My next step will be to test the tacho with a signal generator.

Anybody who has tested a tacho that way?
This seems to be a common problem, any suggestions?

Edited 2002-08-10
RIGHT CAPACITOR ELFA PRODUCT CODES ARE 67-003-63, 33 uF AND 64-013-46 4.7 uF

[Anonymous]

Wow

Well, I have no clue what a condensator is, or even to begin where to look for one on my bike. Can you shed a little light on this for me?

[kz]

First i dont know if the tacho on a GS 650 L -83 is the same as on a GS 1150 -84.

Are you sure it is an electronic tacho and not a mecanical with tacho cable?

[Anonymous]

I think its another name for a capacitor. Also is the product code
64-013-46 correct? I found a 67-013-46 but not the one stated.
Is it a relatively straight forward installation? I am really keen to get my tach working again

[kz]

You are correct JD capacitor is the right word, sorry my english.....

[kz]

sorry for the product code to, 67-013-38 and 67-013-46 is correct I checked twice this time.

Edited 2002-08-10
RIGHT CAPACITOR ELFA PRODUCT CODES ARE 67-003-63, 33 uF AND 64-013-46 4.7 uF

[Anonymous]

no sweat kz, the information you provided has helped me out a great deal and I am extremely grateful for it. I thought i'd have to buy a new tach but instead just a couple of dollars will fix it

[Anonymous]

Mechanical vs. Electronic

I'm pretty sure I have a mechanical tach. I guess i wil just have to go back to my original plan of getting a new tach.

Thanks

[kz]

The whole operation toke me approx. one and half our.

You have to remove the instrumentation cluster from the bike; there is one cable for the gear indicator that has a connector under the tank.

You don?t have to remove the tank completely, it should be possible to disconnect the connector only by loosen the tank. The fairing might have to been dismounted (I have no fairing).

Ones the instrumentation cluster is removed you have to remove the back panel and then loosen the four screws that hold the instrument set.

Pull out the instrumentation set from the housing.

Disconnect the three wire connectors for the tacho and loose the two 7 mm nuts that hold the tacho.

Gently pull out the tacho.

Change the capacitors.

The circuit board is an old one with plating only on one side, so the soldering itself is not a problem.

[kz]

JD,

I would be very interested if you came to the same result as I did.

If you want I can E-mail you a JPEG file of the ciruit board witch I scanned last time this topic was discussed in the old forum.