Im going to ask cause Im not sure but, is the fan really needed other than at very low rpm and at a stop?
The reason I ask is, isnt the cooling fins being exposed to enough air at speed that the fan isnt needed.
On a automobile the fans do nothing to help keep a radiators temperature down over 35mph, the air that is passing through the fins is more than sufficent, thats why they make fan clutches for car/trucks.
I know there is a lot of two-stroke engines that dont have any fans at all, has anyone ever tried to run without the fan(not at an Idle/standstill) for a period of time to see what happens.