Funny thing is ...
The fan kicks in after the same amount of time no matter what the air temperature is, summer or winter. It also seems to be linked to the revs.
If it stays below about 1500 rpm while on choke it doesnt come on, but even slightly above that and wwwhhhhhhhhhhhhiiiiiirrrrrrrrrrrrrrr! If you set off as soon as the fan kicks in and flip the choke off, you can tell its not up to operating temperature. All stuttery and lumpy
Or if you flip the choke off as soon as the fan kicks in and dont set off, tickover drops way too low, which says to me that its not up to operating temp.
I seem to have a vague memory of reading somewhere that its set to come on as a test that the fan is working, and as far as I can tell, it kicks in before the engine is up to temp, or there is any danger of overheating.
Not saying I'm right, just a different angle on the thing
It still bugs me though. Have to park the bike on the side stand at work cos of uneven ground, so I cant knock it into gear to turn the fan off cos
of the side stand cut out.