15-03-12, 05:44 PM
Being intrigued by all the theories I phoned the helpful people at Yamaha UK and spoke with one of their technical bods. First thing he said was that if you're warming the bike to the point that the fan is kicking in you're waiting too long to ride it, you need to get going before it kicks in as by that point it's already overheating. Second thing he said was that the fan kicks in to protect the fans plastics (not the motor) from the heat from the headers, it's not to aid the cooling system as I thought.
So there you have it (and the reason not to fit a cut-off switch).
So there you have it (and the reason not to fit a cut-off switch).