If you change the driven or driver sprockets' number of teeth, obviously the speed sensor will measure badly, but in this case I believe even the original FZ6 display will display wrong speed.
Yes, I saw it, thank you for the link. I'm attaching images from my previous post, because they are there in a bad resolution. I think the location is clear from these images, but still I'm lost.
I measure it between the speed sensor and the ECU on the white/yellow wire that goes to the ECU (grey/black wire in my connectors).
Here is an example of one measurement and calculations based on the measured values...
I'm trying to make my own gear indicator for my FZ6 2007 and I'm curious about where is the speed sensor signal coming from. Based on the values I measured, it looks like one driver sprocket revolution makes ~25 speed sensor pulses, so I guess it measures 5th gear wheel (25 Teeth) or 6th gear (26T).