WHAT IS IT? The Boyesen Supercooler is an aftermarket water pump (cover and impeller) that improves water flow, engine cooling and efficiency.

WHAT’S IT COST? $199.95.

CONTACT? (800) 441-1177 or

WHAT STANDS OUT? Here’s a list of things that stand out with the Boyesen Supercooler water pump and impeller.

(1) Hydrodynamics. Boiled down to its essence (pun intended), the Boyesen Supercooler flows more water than stock water pumps. Boyesen has been working on water pumps since 1999 (during the two-stroke era), and the switch to four-strokes has only made Boyesen’s effort more important. Four-strokes run hot—very hot. The Boyesen Supercooler can reduce engine temperatures by as much as 10 degrees, as confirmed by tests at Team Kawasaki. Internal engine temperatures often rise to levels that cause damage to the cylinder, piston and valve-train components. If these parts become heated beyond the optimal operating temperature, component damage will begin to occur. How does the Supercooler prevent this? Hydrodynamics. Boyesen’s investment-cast-aluminum water pump cover has bigger water inlets, a sculpted design, no casting seams, less restrictive bends, a more efficient impeller shape and less cavitation.

(2) Casting. By casting a totally new water pump cover, Boyesen was able to maximize the flow through the unit. Boyesen’s design takes advantage of everything from Bernoulli’s effect to biological studies.

(3) Internal shape. Stock water pumps aren’t very hydrodynamic. Their internal shape and impeller create excessive air bubbles in the water. Air bubbles lessen not only water flow but the amount of water per cubic gallon. Boyesen’s nautilus-shaped cover and impeller increase pump capacity by eliminating the cavitation that creates air bubbles.

(4) Inlet size. Unlike the stocker, Boyesen’s water inlet has an increasing diameter and artfully curved shape. This is a vast improvement over most stock inlets, which decrease in diameter as they near the impeller and have a 90-degree bend at the pump (a very serious hydrodynamic no-no).

(5) Impeller. Boyesen’s patented, hydrodynamically optimized impeller design is 25 percent more efficient at moving water than the inefficient stocker. The Supercooler impeller is aluminum, while most stock impellers are plastic.

WHAT’S THE SQUAWK? No major complaints.

MXA RATING: If you are a practice rider who goes out for three or four laps at a time, you don’t need a Boyesen Supercooler. In fact, if you race the typical five-lap motos at your local track, you won’t get the full benefit of what the Supercooler offers. It is designed for racers who ride hard and race long motos where heat is a factor in power output. 

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