This High Class Loser gives a couple tips on where to find that pesky speed sensor and how to install a speedometer calibration device. I used a Healtech SpeedoHealer V4 for my bike.
PN: SH-V4-AB + SH-H05
http://amzn.to/2cBJhjW (not the same one but you get the idea)
PO Box 67190
Calgary, Alberta, Canada