Will never get the rear down to what the front head temps are and may not get them down enough to make a great deal of difference. Just experimenting around and will see what I can do to lower the temp some. I know the Parade fan has to take the temps down some at idle, may have to run some duct work back their after I get all I can from richining up the AFR. I don't use the crotch cooler because I believe they keep a certain amount of air off that rear cylinder and I believe it needs all it can get.

Would like to have one of the old 40's Harley copy cats that had the Jugs stuck out in the wind. I believe that was a short run military version! My ol 88 was not that bad, just to much CU. IN. and lower fairing now I guess. I know the 03 rear jug run hotter also but not to this degree.

 

Coupe...I think Buell actually "experimented" with some venting under-and-around the tank with some models to try and get some air back there.

Those 40's models you mentioned....I think those were BMW-like engines (or the same design) built by HD under contract to the military. You know...they did that again with the Canadian military using a one-lung Rotax engine back in the mid-90's. The dealer here still has a couple.

 

Use a Parade fan or Le Nale fan they will keep your engine cool on a hot day sitting still. I had to replace the fan motor the other day. Here is what the fan motor is all about.

http://www.youtube.com/watch?v=UY2Y1ZCFeF8

If you can find a place other than the fan holder the fan is good by it's self.

 

Most of us have already got the Lanale or HD Parade Fan and a lot are running upgraded oil coolers with fans. The Jagg 10 or the New Ultra Cool that is large capacity and has it's own dedicated fan.

The Parade fans alone are not sufficient for long idle periods in traffic on hot days for the stock 2010 Tri's.