Sat Nav v's Speedo

[Nelly]

Ok we or most of us would have seen some input on the "how fast is you FZ6" thread. You will also have seen a number of posts that mention speedo error. I was using my sat nav today to take my son to a football match. I thought I would check if my nav had an difference to my speedo.

Nav FZ6
18mph 20mph
26mph 29mph (For the life of me, I can't get my bike just to sit at 30mph)
36mph 40mph
56mph 60mph
66mph 71mph
76mph 84mph

I had eight satelites tracking me the whole time so it was a reasonable signal. There were a few seconds lag whilst my nav caught up or slowed down. My speedo was also slightly obscured by the nav as I was using the wind screen sucker. So I conclude yes the speedo is way out? or is it. The literature that came with my nav specifically specifies that it is not calibrated to be used as a speed measuring device. So how accurate is a civillian nav? I was always under the impression that there was quite a window of accuracy due to potential military applications. Maybe some of the military guys can answer this.
In one of the posts it has been mentioned that you can get a speedo corrector. What are they and how do they work?

Cheers
Neil

 

[rgatling]

Here's some info for you...

YellR, makers of the YELLOW BOX speedo recalibrator

 

[madmanmaigret]

why doesn't yamaha make this correction at the factory?
it seems like the speedo (based on neil's observations) is about 5mph off. does anyone know why?

 

[Nelly]

Here's some info for you...

YellR, makers of the YELLOW BOX speedo recalibrator

Have you got one? Or has anyone every used one?

 

[rgatling]

Why are the speedos off? I don't know, but it is common on all modern bikes. Check any forum for any make/model and you'll read the same thing.

I have not used one on previous bikes, but have friends that have. It works as promised. If I change my sprockets, I'll buy one to adjust the speedo and odo.

 

[Nelly]

I think its because the speedo is run off of the engine and not the wheel? I don't fully understand it either.

 

[madmanmaigret]

so are most cars but this doesn't seem to affect them....and if that company can fix it im sure yamaha can also.

 

[jeff in ohio]

Motorcycle Consumer New tested the 2007 and reported a 4mph error at 65mph (going by memory here). The problem with your GPS is that it is calculating your rate of travel based on FLAT travel - not up and down hills. So with a non-flat terrain, you will have speed error with your GPS....

 

[Nelly]

so are most cars but this doesn't seem to affect them....and if that company can fix it im sure yamaha can also.

Very true, it just adds to the mystery?

 

[Nelly]

Motorcycle Consumer New tested the 2007 and reported a 4mph error at 65mph (going by memory here). The problem with your GPS is that it is calculating your rate of travel based on FLAT travel - not up and down hills. So with a non-flat terrain, you will have speed error with your GPS....

Happy new year Jeff,

How flat is flat though? I did these speeds on a dual carraige way that was fairly straight and flat. I'm not getting getting at you, I do beleive that the speedo can't be that out? So it makes sense that GPS aren't as accurate as we think.

 

[jfreakman]

speedohealer.com

I bought one after i changed sprockets. Easy to install and simple to set.