Cooling the pig: Adding an oil cooler fan

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.

let me know how it goes

Hey NONE, I have a RTP fan housing less the fan if your interested, gratis. Lets see what you can do with it. PM me with the address. I too have been working on this. I thought a 3' bilge blower might work. But I was looking for a higher cfm blower. I was also trying to come up with some way to blow air onto the front of the cylinders to cool them down as well, because I believe most of the cooling is done at the cylinders, not oil cooler.

Why not a fan off a k75. Always some on eBay. They put out great air.

If you are satisfied with the results take it to the next level and get the motronic to turn the fan off and on.
On 1150 RTPs a relay is sinked to ground thru pin 17 of the motronic ma 2.4.
The relay contacts can be used to automatically and optimally operate the fan.
If you need a contact pin to do this mod, PM me and I'll mail you one.

Sent you a PM. I was toying with using some ducting, i can see how well the housing works.

Any idea how large they are? The ones on the K1200 i had seemed quite a bit bigger then needed for the short oil cooler.

KTM makes a nice fan



Ktm hut

Pelicanparts
Oil cooler thread

Nexus is the ONLY way to fly.......AMHIK

And yes, one strike and you are out for LIFE.

K 75 or 100 is pretty small and looks easy to mount

Could you just cut the queue? You're on a bike.

Or stop at duty free, buy a Toblerone, and get ahead of the line.

I've had a couple ideas in that direction, as well. I'll be keeping an eye on this... When you mount the fan, use rubber to isolate it from the frame, that should help with the noise. I'm also wondering if the oil temp display in the RID can be hacked to provide a signal for the fan to turn on. LCD uses a small voltage to change the state of the crystals in the display, there may be a way to piggyback a relay to, say, the 5th bar so that it turns the fan on when that bar comes on.

I think a thermostat would be a cheaper and easier method.

You never have had the pig offroad in the mud eh? Trying to get unstuck gets the engine hot faster than anything I know of.

Yeah, it's time for a Nexus tho....

There is a large oil passage in the head that runs around the combustion chamber's circumference. Oil picks up heat here and it gets pumped through the cooler. In that respect, its very similar to the way a liquid cooled engine is set up. My bike hasn't overheated (yet), so I'm not entirely sure what set of conditions would have to occur, but I strongly suspect low speeds and high ambient temps are on the list. Boosting airflow through cooler can only help keep oil temps down.

Very likely. But why do cheap and easy when complex and expensive is an option?

You must work for BMW

No, but the philosophy here is song the lines of "why buy one when you can get two for 2x the price!"

Since the topic is semi-hijacked anyway...

Last I looked, NEXUS was issued for one specific vehicle that you'd use to cross, which discouraged me from getting it because I may be traveling on either of my bikes or cars. Did that change? (I'll probably should go and look it up myself, I know ).

My solution to that problem is to get off the interstate and use a small rural crossing: rarely a line. Here in New England, on land-based border to QC, there are many of those border posts.

Still, no solution for getting the pig unstuck when in mud, that's for sure....

No need to hack and kluge and experiment.
The signal is all there already!
Read my post #6
That's how it's done on the police bikes.

Email me for the .pdf wiring diagram if anyone is interested.

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