I ordered up a Boyesen Supercooler for my 2011 WR450 and finally installed it today. It's a quick and easy job overall - slightly more involved than an oil change - and I thought I'd make a quick little write-up about what I learned after installing it.
I've always wanted to know what difference it would actually make in operating temperature, so I took some readings.with my little remote thermometer tool (Harbor Freight's finest...but it works great) before and after install, at the same ambient temperature (90 degrees), under the exact same conditions. So I started it from complete cold each time, let it warm up for one minute, took it for a two-mile warm up ride with a couple of WOT blasts in the same places, then brought it right back to my garage and let it idle for exactly two minutes. I then got the temperature at the head on the right side. Right as the two-minute mark approached each time, before and after install, I got the pictures below. All in all, under idle conditions, I got 209 degrees at the head with stock set up, and then 204 with the Boyesen parts. Temperatures will obviously be higher with a load on the engine and not much airflow (technical sections, tractoring around through the trees in sandy soil, etc and other places where I'm guilty of clutch abuse), and I have a feeling the temperature split (stock temps vs. temps with the Boyesen set up) would be even greater under those conditions than you see at idle with the extra volume of coolant flow at the same air velocity through the radiators. The only other difference between runs was I drained out the factory Yamaha coolant (which was five years old...) and filled up with Maxima Coolanol. There are fancier coolants out there, but I use Maxima everything else so I picked up a bottle of that for the job.
Side note - in the first temperature photo, you will see the laser about 1/2" towards the exhaust side, but I had actually been aiming it at the center and it had settled at 209. Later for the second reading, it had settled at 204 ("settled" = several seconds at the same temp).
At two minute idle in garage with stock Yamaha impeller and coolant:
At two minute idle in garage with Boyesen Supercooler and fresh coolant.
Boyesen Supercooler on the left, stock Yamaha on the right...
I will go ride with it off road tomorrow and get a better feel for the cooling, but as a baseline, there is certainly a bit of an actual improvement that will probably be more prevalent when things start heating up and I get a little air moving through the radiators.
Edited by RockerYZWR, July 03, 2016 - 04:31 PM.