Optimistic speedo
 

I know you guys will have discussed before but as I'm still getting back into Duc's can anyone explain why the speedo is so optimistic. It even says in the book it reads 8% out.
Its this correct and are they all a true amount out.
I live in the land of the Brunstrom, He's the one that is speed mad and they lerk around every corner in Wales so I need to realy know my speed.
Thanks
G

I must still be asleep this morning as I've now read the post below on the 999 speedo.
I must pay more attention.
Thanks anyway
G