Speedometer error GS1000

[renobruce]

I noticed my 78 GS1000 reads fast on the speedo. 60 mph indicated is more like 50. And I think 100 mph is more like 80-85. Is this inherent to these bikes?

[humhead]

Road tests of !000s mention "optimistic" speedos. I don't think they were quite as bad as you 're seeing. Is everything on yuor bike stock?

Terry

[bradleymaynar]

Bruce, how did you come to that conclusion on your speedo? I once thought my speedo was giving me the same way off readings after passing a roadside speed sign. You know, the ones they put in areas where traffic is known to always run over the limit. Anyway, it wasn't long after that that I got myself and 7 other bikes pulled over for speeding in WI. Turns out my speedo wasn't that far off. I think the deputy checked our speed (keeping up with us in the cruiser) as high as 83. That's about the fastest my speedo had said I was going. I've since checked it by following my wife in her car and having her keep a steady speed. Our speedos may exaggerate, but it's not by much.

Brad tt

[runewolf]

Checking my 750 against my GPS it is about 5 -8 mph over what the bike is actually doing. I'm not too concerned over that, if I think I'm going 75 and I'm actually only going 70 maybe I won't get a ticket

[renobruce]

Bruce, how did you come to that conclusion on your speedo?
Brad tt

By comparing it to my 1150. I have run my 1150 through a 5 mile speedo check at 70 mph and it is spot-on. I had a friend on my 1000 following me in that same stretch... I was going 70 and he said the speedo on the 1000 was reading a little over 80.
And the other day, after synching and readjusting the carbs on the 1000, I was getting on it pretty hard from a dead stop, shifting at 8500 rpm. When I was maxed out in third gear shifting into fourth, the speedo said I was going 115 mph. Cruising at 100 indicated just seemed more like 80 or 85.
When I get my parts back from paint, I'll run the bike through that 5 mile speedo check and bring a stop watch.

[renobruce]

Road tests of !000s mention "optimistic" speedos. I don't think they were quite as bad as you 're seeing. Is everything on yuor bike stock?

Terry

Yes, everything is stock.

[Sandy]

With stock gearing you should be running about 3800 rpm at 60 mph (4000@100kph), give or take a bit. Mine as far as I can tell seems pretty close. I'm running a 100/90 on the front.

[humhead]

Here's some numbers from a March 78 test of a 1000.
Indicated Actual
30 mph 27mph
40 mph 35.3 mph
50 mph 44.5 mph
60 mph 53.5 mph

These from an April 79 test of a 1000E.
30mph 25.43mph
60mph 51.48mph

Looks like this was a design flaw.

Terry

[renobruce]

Great info to have, Terry. Thanks! Those number pretty much jive with my bike.

[SqDancerLynn1]

I chalk some of it up to tire sizes Instead of 3.25 or ??? we are using metric # tires. WHile a 100/90/19 is best for handeling a 110/90/19 will be more acurate in relation to the speedo reading

[Sandy]

Here's some numbers from a March 78 test of a 1000.
Indicated Actual
30 mph 27mph
40 mph 35.3 mph
50 mph 44.5 mph
60 mph 53.5 mph

These from an April 79 test of a 1000E.
30mph 25.43mph
60mph 51.48mph

Looks like this was a design flaw.

Terry

WOW!!! Looks like a proper speedo check is in order. Thanks for the info.

[KEITH KRAUSE]

My '79 1000E is about 3-5 mph fast, depending on speeds.
My NOS gauge set reads identical to the original set. Both are fast.
About 66/67 mph at 4K...actual is about 63.
I don't pay much attention to indicated speed shifting from 3rd to 4th, but mine is closer to 100 mph between these shifts. Your indicated 115 seems high. My 4th gear shift to 5th gear is about 115.

[Pharkmeh]

ran mine along side our toyota camry - speedo reads about 12kph too fast...

might help me avoid a ticket or two so its not all bad

[cberkeley]

The speedo on my GS650 is 5% optimistic. Clocked it and the odometer against my Magellan GPS.

[wiredgeorge]

The phenomenom of the optimistic speedometer is not a Suzuki issue. The speedometers used on many metrics from the 70s/80s are magnetic. As time passes, the magnetism decreases and the speedometers grow more and more optimistic. Your speedometer CAN be recalibrated if you don't mind rolling up your sleeves. I will post a link to an article describing how to do it. While the article is for a Beemer, I think it will work on almost any magnetic speedometer. After reading the steps, you may find that it isn't that important to have an accurate speedometer! bwhahaha

http://home.jtan.com/~joe/speedo.htm

FWIW: Almost all motorcycle speedometers are a shade innacurate (optimistic) even on a brand new bike but the old ones get really optimistic. My KZ carb test bikes are all in the range already mentioned... a reading of 60mph is about 50 mph.