PRODUCT EVALUATION:Cool enough to go fast 


By Daniel Gonzalez

The Supercooler impeller (right) has taller vanes that have a closer tolerance to the water-pump cover.


Boyesen has been a front runner in the off-road motorcycle and ATV industry since 1972. Eyvind Boyesen advanced reed-induction technology for two-stroke motors. The name Boyesen soon became a staple for performance on and off the racetrack. Boyesen is known for creating more than just reed-induction products. They offer the Power X-Wing, factory racing clutch covers, Shockout grip system, Quickshot kits and more. We focused on the Supercooler kit. Boyesen understands that a better-flowing cooling system means your engine can retain its horsepower and allow you to push it harder without overheating. We picked up a kit for a Honda TRX450R. The kit includes a redesigned impeller with longer vanes, a matching water-pump cover and an O-ring gasket to perform a proper install for $194.95 or $199.95 for the Spector Series kits.

Top: The Supercooler water-pump cover (right) is cast to have tight tolerances to the impeller rather than the open chamber like the Honda cover on the left.



There can be a variety of factors that cause an engine to overheat. For example, jetting to lean for the performance mods that have been installed. We kept the TRX450R engine stock for a while to learn the engine’s characteristics or weaknesses before installing go-fast parts. Ripping across the desert on a hot day, shredding through the dunes, racing or taxing the engine on steep trail climbs would cause the temp light to flash. In addition to the little red overheating light flashing and, of course, the fan was running (like it should have been) to bring the temps back to a safe level. We would also smell the coolant that had boiled out during the ride and left a mess all over the glide pate. Our goal was to make the factory quad ride comfortably and have the engine run efficiently in stock form before adding engine performance mods. We installed Boyesen’s Supercooler kit for a fraction of the price of installing an oversized radiator.

Now, we can’t tell you GPM (gallons per minute), and we don’t have an accurate temperature comparison.

Boyesen’s investment-cast impeller and pump cover has a sculpted design internally with larger water passages, no casting seams, less restrictive corners and a more efficient impeller. The tolerances are closer between the impeller blades and the pump housing. The Supercooler’s interior is super smooth and is designed to eliminate pinch points as coolant flows in and back out into the cooling system.

Looking into the pump-cover exits, you can see that the Boyesen cover has smoother bends.



The Supercooler kit is quite an impressive unit. Once it’s unwrapped you will notice how Boyesen’s legacy for quality still carries on today. Installing the Supercooler is not too difficult and should only take a couple of hours to install, but make sure you torque all bolts to the recommended torque values in the service manual. Install time would be a good opportunity to check your impeller shaft, bearings and seals, replace your thermostat, get a new radiator cap and get high-quality silicone coolant hoses instead of reusing your stock rubber hoses. Plus, don’t forget to purchase the correct coolant.


After installing the Supercooler kit, we wanted to test it on the same trails and climb the same hills in the same manner that we rode before the Supercooler was installed. We went to a local riding area where the TRX used to flash and puke coolant all over the bike once it was finished with the trail. After a weekend of riding we were relieved to find out that we did not have to top off the coolant reservoir tank. The engine did seem to run cooler. Since we’ve had the Supercooler installed, the machine has done a number of races and plenty of recreational riding where a lot of coolant would normally boil over. Now we ride with confidence knowing the engine is maintaining the most power while racing or climbing hills that most would not want to climb on a quad. Go to or call (800) 441-1177.

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