CAN ANYONE TELL ME WHAT THIS DEVICE IS SUPPOSED TO DO ,,,ITS NOT FITTED TO THE EARLIER YZF750 ONLY ON THE LATER ONES,,,,HAYNES IS NO USE

Did they go to teh fly by wire control instead of having a cable?

Is it the potentiometer?

As far as i know the Throttle Position Sensor (TPS) is a potentiometer (radial variable resistor), the variations in resistance tell the CDI where the throttle is, (ie how much power the rider wants, load on the engine). The CDI can then make small adjustments to the ignition timming (advance / retard) as best suited to the riders needs, engine load, revs]. If it is not connected / not working then the CDI will not have this information and you will not have the advantage of different ignition curves, it should still perform well, just not at it's optimum. You probably would not notice on the road, but on the track / dyno it would soon become evident.

Hope this helps you out, I had a CBR 600 91 modded with 98 motor and messed about a lot with it, never noticed the difference wether the TPS was connected on not, until I put it on a dyno, 91 hp without, 99 with.

Happy biking, PhillipW