Try the speedo excuse that it was not working and get a shop to "fix" it.
I have had my share of speeding tickets, and I must say I got away with so much shit it was not funny, IT WAS GLORIOUS!!!
Triple the speed limit, double it in corners and so on. This was on my Ninga 600 bike, and I loved it. I never had too much problem with speed, just the pizza guy who rearended my bike and caused me to have my hip replaced. Fuck pizza drivers. If I ever get hit and injured again, the other person WILL GO TO THE HOSPITAL, if there not injured. I will however admit them to the hospital, and believe me I am not a Dr.
Some people deserve a good beating for injuring someone else.