RPM gauge accurate up to 6000-7000 then flutters

[secondarybob]

Hi all,
On my 1983 550es, the RPM gauge seems accurate up until about 6000-7000 or so, and then as I increase RPM it flutters and never reads higher than 7000 RPM or so even as the engine is clearly above that RPM and not fluttering as the gauge needle is. I've not been able to find a similar report on the forums and am wondering if this is likely a problem on the sensor end or the display gauge?

Thank you!

[Burque73]

The gauge probably needs some lube on the gears inside it. Do a search on lubricating tachometer or something along those lines. Both my speedo and tachometer get wonky when they need lube.

[secondarybob]

Thanks! I’ll give that a shot

[Griffin]

This tach is electronic, just like on my GS700ES.

And just like on my GS700ES, over time it becomes inconsistent and “bounces”.

i don’t know the fix for it. I just go used to it I guess.

[Nessism]

Most gauges like this have a damping pot, to slow down needle movement and damp vibration. I also don't know how to fix it, but I'll ask a friend that does. He rebuilds a lot of Z1 gauges.

[Burque73]

This tach is electronic, just like on my GS700ES.

And just like on my GS700ES, over time it becomes inconsistent and “bounces”.

i don’t know the fix for it. I just go used to it I guess.

I looked at the parts fiche for the 83 550e and saw a cable drive in the valve cover. Thought that meant the gauge would be mechanical as well.

[Cipher]

I looked at the parts fiche for the 83 550e and saw a cable drive in the valve cover. Thought that meant the gauge would be mechanical as well.

It looks like you can open the cam side "gearbox" If its not an issue with the clock itself it may be a weakened magnet in the "gearbox" assuming its some variation on a "hall effect" sensor.
If it is prices even on ebay are crazy steep for NOS.

Or its a pickup on the harness that attaches to the "gearbox"

sale on " today................... I have tthe clocks somewhere Ill take a look as they are open.

[Rich82GS750TZ]

I looked at the parts fiche for the 83 550e and saw a cable drive in the valve cover. Thought that meant the gauge would be mechanical as well.

Roger, it looks like the cylinder head cover for the 550ES has the gear, but the fiche also shows a plug # 15. I think rather than have a 2 different valve covers for the models that had the traditional analog cable and gauge, vs the electronic tach, you just plug it. This is just a guess.

https://www.partshark.com/oemparts/a/suz/50d3f61cf8700230d8b4c7c2/cylinder-head-cover

[rphillips]

May have been looking cross eyed at it, but what I think I saw was the "83" GS550ED has a cable but the "83" GS550ESD is electric...I's looking on Suzuki Parts Monster's fisch of the speedometer- tachometer.

[Rich82GS750TZ]

That’s what I saw, rphillips. OP has GS 500ES(D=‘83), so electric/electronic tach, like Griffin said.

[Cipher]

Sorry the tach gets a signal from the igniter box directly via a B\Y wire that also ties into an ignition coil.
So clean your contacts at the coil and at the plug that connects the instrument cluster and check for damage to the sheathing.

An odd thing to build and insert a mechanical device to replace the cable system at the head.

Is this heralding the death of a coil or imminent igniter failure?


an update found and dismantled my spare gauges and the wiring diagram appears incorrect or there is a documentation issue across years suppliers etc.

The tach gets fed by three wires. There is a PCB with an IC and other nice things that feeds the tach itself via two wires.
How this is cheaper or better than a cable boggles the mind.

an update again

wiring diagrams are hard to follow on a screen. but........there's quite a few splices that may be suspect as well as tie ins to other components.
Wire feeding the IC is brown on the tach and may well be connecting to the B/Y on the harness side of the connector. ( I don't have it handy to check )
power is supplied by an Orange and a White. Orange is + and White is spliced into other things in the cluster as -

[Burque73]

Roger, it looks like the cylinder head cover for the 550ES has the gear, but the fiche also shows a plug # 15. I think rather than have a 2 different valve covers for the models that had the traditional analog cable and gauge, vs the electronic tach, you just plug it. This is just a guess.
https://www.partshark.com/oemparts/a...der-head-cover

Ah ha, that makes sense. Thanks Rich.

[rphillips]

Yes, a little confusing. It shows both the plug for the hole for "ES" and the gear etc. for the "E" but no mention they both go in the same place. I never figured from the picture. No clue that when using # 15 and 16 you don't use #'s 11, 12, 14, and 10 or vise versa.