[JimGregory]

This morning on the way to work I noticed the tach behaving badly. Was stuck around 3000 rpm. Would move some, but not much. Shut the bike off at stop light and restarted. Same behavior. Later I looked down and it was normal again.
I wonder what that was about??
Jim

 

[Strega]

Check that your battery connections are tight.

 

[DuckMan]

Sometimes my ST3S would do that. And a couple of time the dash would totally die preventing the bike from starting. In about 35000 miles this happened twice. Pulling and reseating the connector on the dash fixed it. But good luck getting to it.


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[HyperJB]

If you have an early ST without a wonky tach I think you are the outlier these days :laugh:

Mine at idle displays about 300 rpms too low and after about 5k gets weird and fluttery. I have heard from multiple folks that cleaning the connections helps, didnt fix mine tho. I believe one guy on here managed to tear one apart and repair the electronic sensor that feeds the RPM data to the tach, but it looked pretty involved.

 

[JimGregory]

After having a bit more time and doing a search, it looks like "Brass Screws, Ground, Connectors, and so on."
All of which are a bitch to get to.
That is the theme of this bike. Bitch to get to.
Oh well. Awesome fun to ride. And frankly with this motor you really don't even need a tach.
Thanks guys!

 

[Sheff928]

Same problems, and a few others, on my Honda Blackbird. Reg-Rec replacement took care of it.

 

[steve__d]

The owner's manual doesn't identify it as such, but the erratic functioning of the tach in reality is an electric system diagnostic display. Unfortunately, the tach bouncing around or standing still or dropping doesn't give the exact problem, but such a problem exists aside from the tach itself. Up to you to spend hours and hours looking for it!! :|

 

[flynnmon]

I've had this happen to my ST2 a couple of times, it was a sign the charging system was going to act up,
Usually the voltage regulator. 2 VR's later, I'm running a Mosfet unit now with good luck.

 

[JimGregory]

I have already got a mosfet regulator under the headlight in the breeze. I have installed a volt meter as well. She runs about 13.8 volts.
Pretty sure it IS the tach or it's connections, because when I tap it, it behaves properly or differently.

 

[HyperJB]

I have already got a mosfet regulator under the headlight in the breeze. I have installed a volt meter as well. She runs about 13.8 volts.
Pretty sure it IS the tach or it's connections, because when I tap it, it behaves properly or differently.

I wish I could find the thread where a guy rebuilt one, but from what i recall there is some sort of wound spring sort of sensor that relays rpm numbers by converting some kind of resistance/ohm number. Black magic to me, but there is a thread out there with an exact fix. Ill look further after work and see if I can drag it up

 

[Sheff928]

I have already got a mosfet regulator under the headlight in the breeze. I have installed a volt meter as well. She runs about 13.8 volts.
Pretty sure it IS the tach or it's connections, because when I tap it, it behaves properly or differently.

So if you already know this why post your question?

I have to say that this grates a bit - I read these forums and questions in good faith, and when I think I can make a useful contribution I do so.
Perhaps it would have been better if you had mentioned at the start that you had replaced the regulator, had a volt meter which reads normal, and that tapping the instrument alters the tach behaviour...

As a matter of good manners, please don't waste the time of others when you know what the problem is.
It sounds like you were just a bit too lazy to investigate the connections, and hoped for some magical solution, from those not too lazy to reply, in order to save yourself the effort of investigating the problem yourself.

 

[JimGregory]

Sheff
I didn't have time to investigate anything. I rode to work and it acted up. So I threw out the question. That's what these forums are for.
I didn't already replace the regulator. Someone before me did. I did not know it could be an issue with tach function. Now I do.
I didn't KNOW tapping on the tach altered the behavior until days AFTER I posted the issue, so not possible to include in first post.
YOU are giving ME lessons on good manners? This is me, right now, exercising good manners. (silence)
I appreciate everyone's help with my various little ST issues. I am new to Ducati.

 

[Sheff928]

Sorry Jim,
Must have been having a bad morning. Please forgive me.

 

[JimGregory]

Roger that. Thanks for the reply!
Jim

 

[JimGregory]

Finally got to digging in to the tach issue. The tach has continued to work properly, then not work properly.
Windscreen and some other bits off, and the gauge cluster was out. The brass screws were quite snug but managed a slight bit of added snugging. All connections looked fine, but I slid that 3 wire connector in and out a bit. Need to get some dielectric grease. Left it on the boat.
I took this opportunity to rewire my 3 wire volt meter. Previously I had tapped the low beam power to turn on the display AND power it. Now the low beam just turns it on, and dedicated wires to the battery now power it. Previously I was losing almost a volt to the ducati low beam wiring. Now it reads full battery power.
So..I will reassemble it tonight and wait for the rain to stop. I really do not feel like I fixed anything, but maybe I did.
I tested it in the garage, and the tach behaved. But that doesn't mean it will continue to behave.

 

[mlukason]

I would avoid dielectric grease. The grease can inhibit electrical contact. If you’re looking to apply something that will improve contact, try something like stabilant 22. The dielectric grease can be used on the plastic surface of the connector to help keep moisture out.


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[JimGregory]

That stuff is pricey!
I did spritz it with deoxit gold. Deoxit has always worked very well for me.
Yes I should have mentioned that.

 

[JimGregory]

Completed the job last night. All wiring done and tied off. Everything worked in the garage by testing with engine running. Low/high beam working as well as they do work which is not very. Tack smooth. Volt meter agreeing with my fluke meter.
Off for a test ride. NICE the tach is still behaving. Did I mention the neutral light went intermittent as well? Well it did, and for whatever reason now it isn't. Nice. But wait. NO SPEEDO. Crap. Back in the garage and off with that fiddly port side cover. My new volt meter wiring makes connecting the speedo cable much harder. Oh well. Figures the only thing I couldn't bench test was left disconnected.
So anyway the tack worked properly once in a row. Lets see how it does today for the ride into work.

 

[JimGregory]

Well the tach worked twice in a row. Sadly the clutch slave went away and I had to abort my commute to work. I had to take my old BMW R100RS to work. That old airhead demands very little of me. This Ducati, not so much!

 

[Yorik]

That old airhead demands very little of me. This Ducati, not so much!

Yet! It just needs a little tidying up. That's all.