my nephew bought a YFZ 450, it has a little black toggle switch set down in the front left fender. it has three positions none of them seem to do anything. it does not have lights so i was thinking that the switch mite be for that.

Hey tom does it have wires hooked to it yFZs have a problem with the temperture sending unit not working so people wire in a switch for the fan
If it has wires on it follow them to see where they go

i followed them and found they went to the plugs for the lights the back light works when the switch is forward and back and i used a test light to check the plugs on the front and has power in on pasition. i didnt know about the heating problem thanks for letting me know. after riding for a half hour of riding the fan never did come on, so maybe i might go ahead and wire in a switch for the fan.

yeah I would so that you wont to worry about haveing big problems later on with the fan not kicking on

Good Job with the diagnostics Mike!