I bought the Wards Part Werks fans about 2 years ago, used them 20,000 miles, and liked them for cooling the heads/cylinders after shutting off the bike...but not so much when running the bike, since they blow a lot of
hot air on my right leg.
About 2 months ago I got some oil cooler fans (see next paragraph) and added them to the bike with the Wards fans, which have a 190* thermal switch in contact with the cylinder fins.
Huge difference. Before, on an 80* day, the WPW fans would run a lot while riding, and often run 20 minutes after bike shutdown. Now, with oil cooler fans, Wards fans only run 2 to 3 minutes after shutdown. Another thing: these oil cooler fans only cost $70.
I have the Big Sky fans
http://bigskyfan.tripod.com/ on my SERGU, but I had to do some mods to fit it into the small space there. The CDA
http://cdavtwinfans.weebly.com/oil-cooling-fan-kits.html probably will fit w/o mods.
I chose the BSF b/c it moves 96 CFM total, while the CDA moves about 78 CFM.