There is a big bug in this project, and I should've taken the bike out for a test ride before posting the original message. Mounting fans in front of the Premium Cooler is a bad idea, and after a ride this afternoon I figured out why. The fender-to-fan clearance is at least 1" when the bike is still. It doesn't stay still, though, and as the forks compress the fender moves up and to the rear at the same angle the forks are oriented. By the time you brake or otherwise compress the forks even moderately, the gap closes dramatically, and the clearance you have sitting still is gone.

Watching this in action, I would say it would be a mistake putting anything more than 1" in front of the cooler, and that might even be too much. If you do, you should artificially compress the forks all the way and check clearance before riding! Most 80mm computer fans are 25mm deep.

Now, all this said, I have yet another hairbrained idea. Mount a second oil cooler like a Jagg on the downtubes and connect it to the original cooler in series. This would be simple, taking minutes (in theory). Then you wouldn't have clearance problems and fans could be installed without problems. Of course, it would look even more **** than my project, conspicuously hanging out on the left side, but would assuredly get lots of questions and glances, admiring and otherwise, I'm sure. Then there's the problem of the wires running along the downtubes, which would be hard to hide. It would look like overkill, I think, and some would say the whole idea of oil-cooler fans is such.

 

Here we go, and this project may not yet be dead. How big is this fan? Your configuration should be the same as mine, and on mine there is precious little room for mounting anything behind the cooler. The VR is in the way. I guess you could raise the VR 1/2" or so, and then the 80" fans might fit. If the Yamaha fan is small enough, maybe it could be mounted diagonally, the top leaning to the front of the bike. That might work if you built a baffle to keep air from being sucked in from the sides.

I need to quit thinking about this. I can see more craziness in my future.

 

The fans are a good idea but!!!! the additional air flow from riding would put to much axial force on the bearing hence reducing the life. those fans are not designed with a thrust bearing to accept the additional loads

 

I assume you mean it would exert pressure when running. The fans I installed were pushing with the wind, so I doubt if there would be much stress on them while running if the bike was moving fast. When not running, they should not be spinning on a brushless motor, although I wouldn't bet on that. If it did spin it would seem that the pressure on the bearings wouldn't be much more than if it was running. I know someone who has computer fans on his Dyna that have lasted for over a year.

 

Could we mount a fan (w/o oil cooler) in the triangular gap in the down tubes? The fan could be turned on, by whatever means, when the engine needs some air flowing by it. I know it would hit the front jug mostly, but any air would be useful. I think this mod could be the most useful and less....well....ugly.

Anyone know where a small radiator fan can be purchased?

Also, another option is to install remote oil coolers in the lowers attached to the crash bar. One could install oil coolers AND fans in those w/o much noticable difference. I don't have lowers, but I was just thinking.

 

Here are some fan options. The 5.2" SPAL low profile fan will blow 313 CFM and only draws 3.6 amps. They also sell a fan control kit that will turn the fan on and off automatically via an adjustablethermostat. Looks like the fan and control kit could be purchased for roughly $100 US.

Anybody know what size fan can fit on the down tubes?

 

http://www.bamph.com/rmh/oilfan.htm
I found this, mounted on the inside.

 

A fan in front would interrupt the air flow to the engine when moving, which I presume is why HD didn't mount their accessory "parade fan" in that location. It is mounted where the stock horn normally resides, as is the LeNale cylinder fan (http://*******.com/2gwpqd).