Speedometer accuracy

Who needs the speedometer?
No just kidding!

I have not tested mine with GPS or any other device so i dont know.
I just go with the flow of the traffic.

Tested mine and against GPS it's around 12% off (high) at town speeds.

Same - I get about 10% variation.

At 33-34mph on the speedo I get a 30mph signal going through 'warning' lights in built up areas.

Same in the car too tho so I put it down to manufacturers meddling with them!

Thanks for the info. This is about what I was thinking. Is this me or all japanese bikes have those kind of discripancies in their speedometers ? And why ? Do they test their bikes with bigger tires ?

All speedometers have this, worldwide, and cars and bikes alike. It originated from claims by people who got a speeding ticket while their speedometers told them they were within the limits. Most manufacturers deliberately make them so they show about 10% higher speed than your actual speed.

That is also why (at least in the Netherlands) when you receive a speeding ticket, they calculate a certain percentage off your actual speed to accommodate for 'false' speedo readings.