I have a 1993 907ie I bought this past summer and so far have been very pleased with the bike.
The bike runs great, except? When the motor temperature rises past 175* and the radiator fan turns on, the idle speed rises to about 2,200rpm.
The only time it happens is when I'm stuck in traffic and at idle, it never (the motor temperature) goes above 175* when in motion. Once I start moving and the temperature starts falling back under 175* and the fan shuts off, normal rpm idle speed returns. (1,000rpm)
Is this normal? Is it suppose to increase idle rpm to make extra volts too run the fan motor? The battery is new and in excellent shape as it's on a battery tender when bike is parked.
I'm thinking it might be an electrical problem?
Any input or ideas will be helpfull.
thanks, Sam...
(assumption is the mother 
you are right on the money as it makes sense to up the
) If the engine has to be hot ( actual temp .... not what the fan t/stat or the temp gauge may be telling you ) for the fault to occur then Id be lookin for extra air getting in there somehow ( I have seen engines suck enough air down knackered valve guides to cause men to go bald scratchin thier heads trying to sort idle speed/ mixture issues ........ not lookin at that @#$%in capri in the driveway 
) .... have fun 
Break. Ha-Ha...