with my first bike i'm working on cooling system for the etek, i have two temp sensors one in the fins on the back of the motor and another in the slot where the rear bolts are by the fins.  the first senser was reading about 11 deg F lower than the second senser in the bolt slot with just an external fan blowing down on the motor.

but with the new fan mounted on the rear plastic cover [cut a hole for air flow] the diference dropped to 7 deg F at low temp and as the temp reached about 160F the difference decressed.

overall temp may or may not be lower this last ride was in 98F weather.  but that new fan on the cover [blowing out] pulls out alot of heat from the motor!  the 25 mile [30 mph average] morning ride out to my workshop when well the motor stayed under 160F [outside air 80F], however on the ride back [98F] i needed to stop half way and get a beer while the motor cooled down [from 170F], but it was funny to hear all the remarks from the harely guys at the biker bar.  they kept wondering whos bike it was.  you might have thought they would ask the only guy working on a laptop [with nasa stickers no less] and not wearing a leather vest.