I have a 2008 WR450F and was about to ghost-ride it off a cliff due to overheating issues. Engine Ice
helped, but not nearly enough for high altitude, warm days, and lots of slow technical riding.
I bought two of the SPAL
4" Paddle Blade PUSH 12V fans from E-bay. It turns out the 4 mounting holes on the fans span the support rods on the front of the radiators nicely. I used 4 Adel clamps on each fan to attach them to the supports with machine screws and lock-nuts (Adel clamps are the little metal cable clamps with the rubber inserts you can get at Ace Hardware). This put the fans right in the center of the radiators, in the front, and keep the engine and radiator heat from cooking the fans. I also have the Clark tank where there isn't enough room to put a fan between the tank and radiators anyway. I cut the factory rock deflectors around the fans using a Dremel and used clear silicon to secure the loose deflector fins to the fan housings. I power the fans with a waterproof on-on switch and a 25amp AC-to-DC module from Radio Shack (total $7.00). Both fans together pull slightly less amps then the headlight. I have the switch on the handlebar
next to my left thumb so I can switch back/forth between the headlight and the fans (when needed). This kept the system simple and I have yet to even come close to overheating!
If you do lots of riding at night, I've found the cooler night temps keep me from having to use the fans very much. If I do need to cool it off, I just stop for a few minutes and run the fans while on high idle and then I'm off again. Obviously you can get more creative if you have a different stator and/or a full DC power system (and ride on the street at night) but I already spent enough on other parts and didn't feel like dumping any more into it. I think I ended up with about $75 in the whole set-up.
On a different note, I don't run the fans at the same time we're blazing down a trail and someone in front of me is kicking up rocks and dirt. Don't need to for cooling. However, when they are not running they have protected my radiator as well as the facotry deflectors do and still don't show any damage after a year.
Edited by Mtn-Track, March 26, 2012 - 01:24 PM.