Modern Vespa

Hi guys. New member here and proud owner of a recently purchased 2006 GT200L! I greatly enjoy riding this little scoot but wish I could rely on the speedometer reading. When doing 40mph per the speedo I'm actually doing only around 35mph. I know this from various speed warning signs showing my actual speed as well as gps on my phone navigation app.

Anyone else had this problem? I'm sure someone will tell me not to rely on the radar speed sign readings and gps but they are very accurate when in my cars. This is a BIG difference not just a mile or two.

Is there a fix or should I just manually mark the correct speeds on my speedo? Any and all comments are appreciated.

Unfortunately, they're all like that.

And the GT200 speedo is purely mechanical, with no calibration possible.

The closest I've heard is changing tire size to force the speedo to read a little closer to reality.

When I had one, I would just "speed" a little to compensate. Not a big deal.

I agree with op. I have 2006 250 Gts and if I actually want to drive 50 km/h, I have to speed up nearly 60 km/h by the meter.

So keep on speeding .

Thanks for the info. Guess I'll just mark the speedometer for the two or three speed limits that really matter. Gotta wonder, though, why Vespa wouldn't make a speedo that works like it should.

It's law in some countries.

https://www.google.com/search?q=motorcycle+speedo+accuracy

Very interesting thanks for the link. I've been riding Harleys for years and have always had accurate speedos. Never would have guessed that some manufacturers purposely make them read lower.

The speedometers are optimistic on all five of my scooters.

Three Vespas and two Yamahas.

Knowing that they are five to ten percent off, and that you typically are safe from speeding tickets up to ten mph over the limit in the US, I ride ten mph faster, as seen on the scooter, than the posted speed limit.

Bill

On my US GTS:

Looks like you're running very slow on an empty tank. How do you keep your water temp so low?

Those are the 20, 30, 40, 50, 60, 70 and 80 mph true GPS marks.

Being an analogue magnet-driven speedo, it starts at just over 5 mph because the magnet doesn't generate enough eddy current (and thus the opposing force) to get the needle's hidden disc to start moving until then - plus it's almost illegally optimistic at the lower end.

The GTS300 HPE I owned was a full 10% 'optimistic' in it's speedo readings.

I just learned to mentally subtract a generic 5 mph from whatever it was reading at any speed.

My wife's Triumph Speedmaster is within a mile or two from exact at highway speeds, while my Triumph Rocket 3R's speedometer is annoyingly inaccurate at highway speeds, at least 10%.

Our Subaru Crosstrek, Ford F-150, and Miata MX-5 are all accurate to within one mile an hour at any speed.

It's nothing new with motorbikes, and I can clearly recall that my Japanese bikes back in the 1970's all had from 5-10% optimistic speedometer error, so it's been like that for a very long time.

which is a common method put poor in my opinion.

I ride at 44 in a 40 zone, 66 in a 60 zone, 110 in a 100 zone. simple and more accurate than sub 5mph.

That, of course, is the proper 10% mental speed adjustment appropriate for your machine.

We currently have four bikes, and their speedo accuracies vary from almost ok, to not ok at all

As such, I'm not going to custom fit my mental speed estimates to suit each bike's differences, and just go with 'good enough' for the entire fleet.

Speedo accuracy at 100-110 mph is almost irrelevant where I live. It's a fun little speed spike now and then, but either is 'go to jail time' if things go badly.

I would say that 75% of my riding miles on any of our bikes is done between 50 and 75 true mph, and my 5 mph offset is practical enough to be usefully accurate under almost all circumstances.

It might not be the best, but it's good enough.

Thanks to you all for your input! I'll just do the mental ten percent adjustment and that'll be close enough.