Wr500 yamaha

 That Fan  set up is quite ingenious! 

Mounting it to the YZ250 Radiator shroud 'fixings' you've done, doubly so!

One fan, or Two (one each side) being used?

I assume at the rear of the fan I can see an air duct directing the forced air down to the head?

All very clever, and, very practical.

One day, I want to fit a "Finner" top end to my PDS'd CRE - to bring it evermore to being a very simple bike. In my plans to do so, I have Fans in mind. As I already have fans on the Radiators of the bike, to stop it from being a Kettle, in tight, extreme terrain. That, and doing head mods that we'd do, decades ago, to get rid of (well, limit) the 500 Air Cooled Ping / Death knocks.

I assume you've got the head sorted on your WR? - they are far nicer bikes with that done.

Brilliant stuff - Well done!

I love seeing peoples Good, Clever work!