Electrical Tachometer Floating...

[victorgallas]

Hey

I have a 1985 GS550ES and it has the electrical Tachometer.
I finnally was able to take the bike for a spin last night after a two year slow restoration process and I noticed how my Tachometer would work fine at idle but then at around 3500 it would stick and sometimes it would fly out to 9k when you know the engine is not even that fast then it would come back.
I have done the typical checking wires, fuses and contacts and all.
But havent had a chance to dig too deep into this.

Can anyone give me any advice to this? I also noticed that when I click the turn signal switch, the tach will bounce up slightly by like 500 or so then move back.
I checked my system voltage with the bike running and its withing the voltage levels described on the manual. I did notice that my rectifier gets rather hot to the touch while the engine is running. Is this normal? Or are they supposed to stay rather cool, or slightly above room temperature?
Also battery is new and its fully charged and tested.

Any ideas are welcomed.

Thanks

[TalonX]

Hey electric tach buddy, looks like we're in the same boat. I just posted a thread on this and haven't had any luck with replies either. My tach 'appears' to work in 4th gear but since it doesn't work in any other gear...who knows. I'd love to take it apart but since I don't have another bike I don't want to unless I know exactly what I'm getting into. I've seen several threads on the manual tachs but nothing on these guys. Maybe it still is as simple as cleaning it?

[victorgallas]

Hey

I saw youre post and then when I got the bike out I noticed the same issue.
But I think I got it working now.
I did a search on google for electronic tachometer floating issues.
Turns out that for many people what caused this issue was a failing, or dying voltage regulator.
Since the stator on the engine outputs an AC current, the voltage regulator uses diodes to turn the wave voltage into a linear constant voltage, or DC.
However when a voltage regulator begins to fail, you may still read good DC voltage with a multimeter, but that does not mean that the voltage coming out of the voltage regulator is a perfect linear DC current. What happens when the Voltage regulator is failing is that you will have some AC waves and pulse leak onto the DC circuit of the bike, and because a tachometer is nothing more than a analog multimeter, it will pick up on these pulses.

I was able to make this go away on my bike temporarily by cleaning the contacts of the regulator really good, of course it decided to come back once a while, since the regulator is not good. So I ordered a new one.

Do, of course, go trough youre wiring harness and connectors on the dash and clean all the contacts as best as you can. This is ensure everything is good. Make sure the ground wire from the dash to the ground post on the battery has no resistance. THis would create a poor ground and add to the troubles of the tachometer.

And what I saw some people do on some other forums for old cars and bikes as a test was to disconnect the voltage regulator from the electrical system and see what it does.

Give it a shot.
YEah I wish more people would know more about the electronic tach, but it seems that it is a rather rare thing...

let me know how it goes for you

Hey electric tach buddy, looks like we're in the same boat. I just posted a thread on this and haven't had any luck with replies either. My tach 'appears' to work in 4th gear but since it doesn't work in any other gear...who knows. I'd love to take it apart but since I don't have another bike I don't want to unless I know exactly what I'm getting into. I've seen several threads on the manual tachs but nothing on these guys. Maybe it still is as simple as cleaning it?

[TalonX]

Ah I see, that makes a lot of sense. I'll give the voltage regulator a scrub down and see if that fixes it, then buy a new one if I have the same problem. Is the regulator part of the rectifier or can they be purchased separately? The entire rectifier assembly isn't cheap on bikebandit. Also, did you happen to find a schematic somewhere on the internet for the gauges or did you just take the cluster apart? Thanks for the help!

[victorgallas]

The voltage regulator is another name for the rectifier, so its the same unit that I was referring to. I spent 99 at Electrosport. I used their rectifier on our Formula SAE cars at school and based on the data logged from our ECU, the voltage output of the electrosport units are really good and steady.

I never found any schematics for the cluster, I just took it apart. Not too hard, just take youre time and be gentle so you dont break any of the plastics.

Ah I see, that makes a lot of sense. I'll give the voltage regulator a scrub down and see if that fixes it, then buy a new one if I have the same problem. Is the regulator part of the rectifier or can they be purchased separately? The entire rectifier assembly isn't cheap on bikebandit. Also, did you happen to find a schematic somewhere on the internet for the gauges or did you just take the cluster apart? Thanks for the help!

[greg78gs750]

the electronic tachy no worky syndrome is common on the es's. plenty have tried swapping capacitors etc in the circuit board, with mixed success....some of the problem seems to be with the aging proprietary main chip in the board. several threads on this should come up in a search, but they probably wont help you much.....

[TalonX]

Ah that's a lot easier to swallow than $230 at bikebandit! I wasn't sure if the regulator and rectifier were one part as it shows them as separate in the service manual I was able to take a look at. Is it a direct bolt in?

[victorgallas]

Yeah its a direct bolt on and plug.
Do check youre connections to the harness to make sure you have a good contact. Specially on the ground wire. I have been suggested to add an additional wire that goes from the regulator ground directly to the battery to ensure a good ground.

Ah that's a lot easier to swallow than $230 at bikebandit! I wasn't sure if the regulator and rectifier were one part as it shows them as separate in the service manual I was able to take a look at. Is it a direct bolt in?

[victorgallas]

Yeah I figured that it would be like that.
I do have a spare dash that has the mechanical setup. If my electronic dies, then ill switch over to the mechanical system.

But I will take a closer look on the electronic components of the tach later then. Perhaps some re-soldering and adding a capacitor to filter out noise should do the trick.. LEt me pull that oscilloscope out hahaha

the electronic tachy no worky syndrome is common on the es's. plenty have tried swapping capacitors etc in the circuit board, with mixed success....some of the problem seems to be with the aging proprietary main chip in the board. several threads on this should come up in a search, but they probably wont help you much.....