Well just spent the last 40 minutes writing a reply only for my computer to crash!!!!!!
Anyway, yes you've kind of understood me, right.
What you need to be looking for here is the switching of the 5V-0V-5V-0V and so on as the wheel is rotated in the direction of rotation, this is what the instument cluster is looking for, the frequency of the 0V's to 5V's it is putting out, this is what is giving the speedo reading or number of rotations of the rear wheel = your indicated road speed.
If you are'nt getting a 0V and just a constant 5V at that connector then there is a problem with the sensor (possibly!).
If you are getting the 'SWITCHING' in voltage you need to work forward now. Check at the C.D.I unit (DO NOT UNPLUG THIS WITH THE IGNITION ON !!!!!) you now need to check the 'WHITE' wire at the C.D.I (with the connector unplugged) and also at the back of the clocks (the WHITE wire remains the same colour throughout the entire loom) Piggyback the test lead into the back of the clocks (WHITE wire again) and use the BATTERY negative pole for your earth, now switch on the iginition, If you get 4.54V at both these points atleast there is some consistancy here in the voltages.
Also another test to carry out here is with the ignition OFF unplug the clocks, C.D.I & the speed sensor and check the 'WHITE wires continuity to EARTH, if your getting a continuity reading then theres a fault in the loom somewhere (it's shorted to EARTH), and this is possibly why your not getting the 'SWITCHING' reading at the speed sensor, and obviously no speedo reading
Let me know how you get on, also is the bike fitted with an alarm at all ?
chitsu.