Slow Speedo

[starfield]

Hi,
Sorry if this is the wrong forum but there does not seem to be one that covers things like speedometers so this was closest.

My 1978 GS550ec has a speedo needle that seems to run in treacle. It takes a long time time to get up to your actual speed and an equally long time to wind the mph off again. I am talking over a minute to react to actual bike speed changes and I am not sure it ever gets up to the actual speed the bike is doing.

I have checked the cable and it spins freely so I am pretty sure the problem is in the mechanism. I was hoping that using the bike regularly would improve matters as it had been laid up for some time but a few weeks down the road and it has not improved at all.

Don't want to replace it unless absolutely necessary as I will then lose the true mileage. The odometer parts functions correctly incidentally.

I took the bottom plate of the instrument binnacle but could not see any obvious way to get any lubrication or cleaning fluid inside.

Any advice welcome or should I just fit a digital bicycle speedo.

Thanks

Peter

[Nessism]

Peter,
These old speedometers are problematic and generally not serviceable. The odometer is a geared drive so it's relatively accurate, but the speedometer and tach needle work off a rotating magnetic wheel with matching metal cup (which responds to the wheel speed thus moving the needle) and when the needle damping mechanism ages issues ensue. Typically the needle osculates or the accuracy goes off like in your case. Only solution is to try to lube the assembly. Some people report success by shooting light oil in though the cable opening, and others have opened the assembly by prying off the front bezel with a small screwdriver and lubricated the mechanism with furniture polish or the like. I've tried both methods without success so just be aware that there may not be a solution short of replacing the speedometer.

Good luck

[starfield]

Thanks for response. Have fitted a bicycle computer/speedo for the time being. Come the spring and better weather I might have a go at stripping the old speedo. In the interim, I will keep an eye on ebay to see if something suitable comes up.

Peter

[BassCliff]

Greetings and Salutations!!

Hi Mr. starfield,

In the Garage Section of the GSR homepage there is an article about getting into your gauges by cutting them open. But you can pry the front bezel off...



Then you can clean out the bell shaped magnetic housing that actuates that watchspring assembly that turns the needle...



If it's just dirty, it's possible to get it going again. If there are any worn gears or springs then you may be out of luck.

Let me share some more GS lovin'.

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If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

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Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[ChicagoBob]

I switched to a Trail Tech Vapor speedo/tach unit for a while. Very compact, lightweight, simple and accurate.

I later went back to the stock tach, then the speedo, only because I liked its traditional appearance (and that red lighting)

[north49]

Starfield...your speedo seems to be running in treacle because basically it is running in treacle. Thre lubricant around the needle bushing turns to syrup with age. You will need to clean the old lubricant out and replace with a light oil.
1.Mark the rotating cup with a felt tip marker. You need to do this so you can replace the needle in the same place
2. remove the needle by prying up evenly on bothe sides.
3. remove the face plate
4. with the faceplate removed, you'll see a brass bushing with a brass nut holding the needle support in the centre of the speedo.
5. inside the bushing is where all the treacle is. CAREFULLY use a Q tip or something similar dipped in laquer thinner to get the old lubricant out of the bushing and off of everthing else in the vicinity. Be carefull with the thinner because if it gets on any of the odometer numbers it will disolve them.
6. after cleaning. lubricating and reassembling the bushing, replace the dial. Using the mark you made on the magnetic cup, re-install the needle in the same location as you removed it. There should be just a slight resistance as it rests on the pin at O mph.
7. this can happen with your tach as well so be prepared. Buying another used speedo/tach may or may not help. Most Japaneese instruments seem to get this condition after about 30 years, but they all can be cleaned up and made good for another 30 years.