Installing a Radiator Fan

I did this as an experiment and so far it's working.  Sometimes when I'm running my bike in very slow tight terrain or sitting in traffic (this is very rare but it happens), I can hear the coolant boiling.  This isn't a big problem with a WR400 because it has a coolant reservoir that captures the overflow.  When the bike cools off, the coolant is drawn back into the radiator as needed.  But, I like to tinker and I thought it would be nice to have a fan to see how it works.

I went to Skycraft and bought a 12 volt, 0.6 amp brushless muffin fan.  Something like this would also work well.  It is wired into the main electrical wire before the main switch, so it can run whether or not the lighting circuit has been switched on.  I used safety wires to tie the fan onto the radiator through the tubes and fins on the front of the left radiator.  It is attached directly to the radiator.  The Devol guards protect the fan nicely. 
In the first version of my fan install, I safety wired the fan to the guards themselves but I didn't get as much airflow through the radiators with the fan on as I would have liked.  With the fan directly mounted to the radiator, the fan makes much more of a breeze through the radiator.

I haven't used the fan very often, but like I said, it does make a pretty good breeze blow through the radiator.  Also, I am pleased with the fan's resistance to water so far.  I have washed the bike quite a few times with the fan installed and have been through some very deep puddles.  So far, it's working like a champ.  One time I got some vegetation stuck in the fan and it didn't want to spin.  I cleaned it out and it began working properly again.

Here are the handlebar switches:

Picture of the fan close up:

Picture of the whole radiator: