The GS has been the best bike i've had thus far. It's taken me through 23 states and 2 countries through the short 2.5 years (and 41,000 miles) we have been together. Although there are many modifications on the market for all sorts of issues or qualms, not much is on the market to help with cooling these pigs. The GS-P kits are available through BMW, not cheap or easy to find though. RT-P oil cooler fans and shrouds can be found, but are not plug and play. I've read of people using 12v fans from computers or electronics with success, but have not seen any write-ups or even pictures. This is the route i decided to go
After some measurements, i visited McMaster-Carr and found a nice little fan that i will be using for the project. Measuring 3.15"x3.15"x1.5", it's a touch large, but it is spec'd at pulling 130cfm of air.
The fan is not advertised as being waterproof or even water resistant. No idea how long it will last, but it is a starting point.
Picture showing how it will be mounted. As seen in the picture, the fan fits under the crossmember and extends down to the top of the light bar. Ignore the yellow wire, using that to help hold the fan up while i take a picture. Did a quick jumper wire just to see it run. Fan winds up a little slow and is pretty damned loud when running (71dB), but it moves quite a bit of air.
The goal of the project is to allow the bike to move at slower speeds off road and in traffic without worrying about the oil temp rising to 7+ bars (260F+). Although the police bikes use thermoswitchs to turn on the fan, i plan to use a simple on/off switch on the bars down by the triple tree.