Tachometer false reading

[DonSimon]

2012 800
With engine off tacho rests below zero. Engine on, significantly under-reading true revs. Is there a way to recalibrate - I have the computer lead and Triumph program on laptop, can you do something in there?
All other electrics/instrumentation seems to be fine.
Thanks, DonSimon

[UncleGary]

Originally Posted by DonSimon

2012 800
With engine off tacho rests below zero. Engine on, significantly under-reading true revs. Is there a way to recalibrate - I have the computer lead and Triumph program on laptop, can you do something in there?
All other electrics/instrumentation seems to be fine.
Thanks, DonSimon

Hello and welcome!
The needle should point accurately to zero when the engine is off of course. When you turn the key to the start position and the display does its self-test does the needle go to 12k and return to less than zero? What does your software indicate for idle rpm?

I have no information about calibration. That would seem to be a dealer/manufacturer level repair if it is possible at all. I was under the impression that the needle rests on a stop at zero. If the stop is broken then the needle just rests at some point of equilibrium.

[T800XC]

There's no software calibration available to fix the needle position. It sounds like the needle has come loose. You should be able to dismantle the clocks and reposition the needle. I've done this before.

[DonSimon]

Thanks for your replies. Tried to upload a 5 second video but can't seem to anymore either here or via Photo Gallery.
On ignition, needle starts from below zero (maybe it's about minus 3K) and swings round to 9K, then returns to minus 3K.
Anyway, sounds like a unit dismantle.

[KildareMan]

It's easy to remove clocks, separate case and easy off the tach needle, then reapply.

[DonSimon]

Ha that depends upon motor skills. Thanks for your interest: do you need to take off the whole unit, or can you somehow prise of the glass and attack it like that? I always think that once you start delving into these electronic/computer gizmos that you might fix the tacho only to find something else is now awry when you've manhandled everything back into place.

[Londonglide]

The Android App Tune ECU  has a check function for the instruments where it will send the tacho needle to a certain number of revs. If you have the OBD access, it will quickly show you if its correct ( It sounds like its out of position)
I'm not sure if our own Tiger Tool can do this?

[characticus]

A good tip for removing the needle (once you get to that stage) is to use two teaspoons positioned with the base of the spoons on the face of the tacho with the round part of each spoon on opposite sides of the needle. Press down gently on the handles and this should lift the needle off without bending or breaking the shaft.

[DonSimon]

All fabulous replies - great forum - and I have two teaspoons (both a bit grody but I shall polish with Goddard's Silver Plate Powder beforehand) and not attempt procedure anywhere around 4:00PM. And I DO have the ECM cable and the program on laptop so shall certainly delve there first!
DonSimon, Mexico
"the only economy in which I believe is the economy of effort"

[Londonglide]

Originally Posted by characticus

A good tip for removing the needle (once you get to that stage) is to use two teaspoons positioned with the base of the spoons on the face of the tacho with the round part of each spoon on opposite sides of the needle. Press down gently on the handles and this should lift the needle off without bending or breaking the shaft.

One thing I see from removing watch hands, is to cut a small slot in something like  a piece of X-ray film to slide across the tacho face to prevent marking the surface, but like a button polisher type of thing.