Modern Vespa

My 2007 250GTS speedometer reads 8mph high i.e., speedo indicates 50mph, actual speed is 42... Dealer indicates he sees no physical problem, and is unaware of any adjustments that can be made. VESPA Customer Support does not respond to emails...

Error has been checked (and verified) by police radar, traffic speed roadside units, gps, and other vehicles.

Any input or guidance would be much appreciated.

They're all off approximately 10% but the odometers are much more accurate (not right on but not far off).
Every European-made motorcycle that I have owned that was built from the 80's-forward have this same, approximate 10% error. Piaggio knows all about it but is very unresponsive to these types of inquiries from their customers from posts that I've read from other members. Either put a small GPS or a good, bicycle speedometer on your scoot if you're worried about it. I just calculate the error in my head and drive accordingly.

Which is worse for you:
Going slower than you think you are, or going faster?

In terms of liability for a company, which do you think is worse for Piaggio?

Thusly, you have your answer.

This is normal even for motorcycles. I just ride between 75-80mph indicated knowing I'm actually travelling about 73ish mph GPS...with traffic in California in-city highways.

Yes, just pick a (GPS) speed you're comfortable with (e.g. 65mph) and add about 5-7mph above that and ride at that speed (about 72mph indictated).

Very normal, sorry.

Oh, and btw, your front brake will make a whirrrring sound. That is normal too.

Oh, and you are going to get way more chicks on your scoot than you did in a car. That is normal.

Or, just open up the throttle and ride it like you stole it.

Guess that just works on my 150.

They all read about 10% fast.

So did my BMW R80ST, and every other motorcycle I've ever owned.

Subtracting 10% is easy to do in your head, if it makes a difference to you.

P.

Like everyone else said ...it's the nature of the beast. I went to a place in Tacoma that had calibrated my old BMW airhead speedo.....they took one look at the GTS speedo and said what pain in the butt that would be.

So when I go 70 on the scooter I know it's really around 65 or so. In 38 years of riding the only speedo I've seen that was nearly dead on was my 1980 Moto Guzzi SP1000.

Certainly got a lot of quick responses, thanks for the input... Any recommendations for a decent GPS for the scoot?

Just put a 130 front tyre on this helps..

Guzzi? It must have been broken, then.

I had a Penton that was calibrated to less than 1/2 mph of the face reading but it was a vdo speedo unit and it could be adjusted.

look at installing this
http://trailtech.net/computers.html