tach and speedo sluggish at best

[PAGS550]

i have a '78 GS 550 that sat for 30 years....runs gr8 except tach and speedo respond VERY slowly if at all.. i was told be someone to remove and sit them upside down with penetrating oil in them...this did nothing...then someone told me they actually have magnets inside that need cleaned up to make them work properly...any help?? everything about this bike is in very good to excellent condition and this is the only problem that exists...

[Steve]

There are magnets and other moving bits inside that need to be in a clean, well-oiled environment. You might have to open them up to do the job properly.

My condolences on your bike running "gr8". Maybe you can get it up to "gr9" or "gr10" some time.
Maybe, eventually, it will even run "GREAT".

Many of us don't use 'texting' shortcuts and have a hard time reading them.

.

[koolaid_kid]

Steve, ur showing ur age.

[Steve]

Steve, ur showing ur age.

And you think you are younger than me?

By the way, the "Y" and "O" keys seem to be stuck on your keyboard.

.

[argonsagas]

There will be magnets, but they are inside the case for each instrument.


The most common problem with "slow" instruments IS the cable, as it gets dirty over time and/or loses lubrication. Either way, the friction inside the cable sheath builds up and impedes the rotation.


Try removing them again, then pull out the inner cable and soak everything in standard paint thinner or even gasoline (outside the house or garage, of course) for an hour or so, then drain them. That should dissolve any dried/caked grease that is inside,

After that let everything dry and then apply cable lube to the inner cable ...do not skimp on it.....
While holding the sheath vertical, add a couple of drops of oil, and let it run through.and put it all back in place.







.

[BassCliff]

Hi,

Remove the individual gauges from the gauge housing. Then with a small screwdriver and needle nose pliers, carefully bend the bezel around the face of the gauge to remove it. Then the innards can be removed and cleaned up.





Reassemble and use a small hammer and punch tool to carefully bend the bezel back in place around the gauge face.



This procedure ( How to get inside your gauges ) is a little more invasive but you may want to look at it for reference.


Thank you for your indulgence,

BassCliff

[rustybronco]

Ron, I would like to respectfully disagree with you. (and you have my respect)

In my minds eye, all a poorly lubricated speedometer cable would cause is the core to stick, resulting in the 'core' winding up until it releases. This would cause the gauge's needle to jump but not have any cause for the gauges sluggish operation. Sluggish operation could only be the result of lubrication that has hardened (dried up) over time, friction between the needles shaft and bearings from having little or no lubrication, or mechanical damage to the drive unit at the wheel.

[mpencegs]

I rebuilt my tach like they mentioned as it was doing the exact same thing. Had old dried oil and dirt in there. Once all was clean it works like a champ.. But my bike only sat 25 years..

[Agemax]

i would have to agree with RustyB as well. the cable for the tacho and speedo is driven from a mechanical drive that will spin as fast as its driven whether dirty or not. it will not go slower than the gears it is driven by.
the problem has to lie in the speedo/tacho mechanism itself.

[mrbill5491]

I don't know, I have 3 sets of gauges that pretty much do the same thing. Two of the tachs are about 2,000 rpm slow, the original tach flops all over the place. All have been cleaned and lubed. one speedosis slow. About 10-15 mph slow. Another speedo just doesn't work period, and the original speedo flops around as well. And that cable is clean and lubed too. Even checked the gear drives, those are fine. Seens like the magnets have lost some of their juice and just won't drive the gauges right anymore. Cables have no weak spots. If I can't get this last set to operate right, Vapor here I come.

[rustybronco]

On the needle shaft inside of the gauges there is a friction dampener. If it goes bad the needle will bounce around. Also there are other reasons for the gauges to read incorrectly. Worn pivots and bushings, rusted or damaged hair springs, incorrect placement of the needle and a damaged bell are just a few of the possible reasons.

[mrbill5491]

On the needle shaft inside of the gauges there is a friction dampener. If it goes bad the needle will bounce around. Also there are other reasons for the gauges to read incorrectly. Worn pivots and bushings, rusted or damaged hair springs, incorrect placement of the needle and a damaged bell are just a few of the possible reasons.

The Vapor set up sounds better every day....getting tired of missing with this other crap.

[Roy]

Please let us know what works for you. I took my '77 GS550 out for a spin and noticed it's doing the same thing. It's not even that cold out there (47ºF) but the bike has been sitting for a week at a time between rides. This is the first winter I've owned it, and I'm wondering if it is just from the cold oil in the mechanism there. Otherwise, hey, mine runs GR8 too!

[collinsra]

I have this exact same issue on my 77 gs550. I'll do some disassembly tomorrow and post my results. Best forum ever.