Speedometer error GS1000

[stanski68]

gps on bike

I mounted a handheld GPS on my bike, ........they give you exact mph.
I had use of a radar gun and they were identical, Anyway the magazine article was correct at 60 mph you are actually going 53, or seven off.
What they did not tell you is it gets worse the faster you go. The GPS also keeps track of top speed, I thought I hit 110 from my speedo, the gps does not lie I only went 93.9mph!!!!
Maybe this is a good thing.

PS the odometer is more accurate because average speed is lower
97 miles indicated was actually 91
The reason I did this was to calculate gas mileage my 1979 GS1000e gets between 26-29 with a cut up air box, and probably jetted, stock pipes.
So if you are calculating gas mileage with your odometer it is worse than you think.

[KEITH KRAUSE]

Not sure what exact mods you have, but 26-29 is low. Typical pod/pipe mod's on a correctly jetted '78/79 1000 will take about 4 mpg from stock mileage, if ridden nearly the same.
How do you drive the bike? Fast or normal? What main jet, jet needle e-clip position (stock needle?) and pilot jet do you run? How are your pilot fuel screws and side air screws set? What color are your plugs after just "general" riding around? Have you ever checked compression?
Not trying to turn this into a tech problem. Just wondering why the poor mileage from a "cut up airbox" and stock pipe.
No, it's not typical of this bike. Not if correctly tuned/jetted.

[stanski68]

79 GS1000E Gas Mileage

I drive it fast AND normal, I just calculated it again and I got 27 mpg.
I just have never had the carbs apart..... the plugs look like it is running rich, but it runs great, ildes at 1200 to 1400, and does not have any flat spots.
Back to the speedo I went 107 on gps and speedo showed 120.