Boyesen Supercooler Water Pump Kit

Vital Rating:
Tested: Boyesen Supercooler
Vital Review

You know the drill... the combustion of fuel and oxygen in our bike's engines creates power, and while this reaction propels it through a series of mechanical functions, it also creates heat. The faster you are, or the longer the motos, the higher the heat. At a certain point, the higher temperatures become the enemy when it gets to the point where it decreases power and reliability. Of course, most modern bikes are water-cooled to keep the temperatures in check, but Boyesen has tried to improve one of the most important aspects, the water pump, with their Supercooler.

Boyesen Supercooler Features:

Two-piece cast aluminum construction.

Increased coolant flow at all RPM ranges.

Patented Nautilus style impeller for hydrodynamic efficiency.

Price $189.99 - $219.99.

First Impressions

At first glance, the Boyesen Supercooler is visually larger than the stock Kawasaki unit. This is because the Supercooler's impeller is larger, which means that the housing has to be larger to accept it. The Boyesen Supercooler also features smoother transitions and surfaces internally, allowing the water to flow without as much resistance throughout the water pump. Think of it as a porting job for your water pump.

The Supercooler that arrived for us is also part of Boyesen's Spectra series. While the Supercooler is available in silver, black, and magnesium on most models, the Spectra series also offers colors that are more desirable for certain bikes. In this case, I received a blue water pump to outfit our 2015 KX450F.

As for the installation, it was fairly simple. First, I drained the coolant, loosened and removed the bolts holding on the stock cover, and removed it from the water pump hose. As for the stock impeller, most can be removed if you place the bike in gear and hold down the rear brake pedal (since the water pump is driven off the engine, it will turn over the engine when it's turned). As for the new water pump impeller, simply reverse the steps while using the recommended torque specs for the impeller. The impeller is not the strongest part in the engine, so overtightening it can break the part. Then install the new gasket, place the dowels from the stock cover into the Boyesen unit, tighten it back down, and refill the bike with coolant.

On the Track

So how did I compare the before and after performance of the Supercooler while riding? I decided to monitor it with a temperature sensor. To do this, I cut a radiator hose and installed an in-line sensor which had a digital meter, so I could view the temperature in real-time. The results were fairly obvious, as I tested this with the stock water pump and Boyesen one within about 20 minutes of each other. The Boyesen unit runs a couple degrees cooler at idle, and I saw as high as an eight degree temperature swing when riding at pace.

As for how the Supercooler aids in perfromance, specifically in EFI bikes, you can get more info by checking out this interview we did with the Boyesen staff last year - Boyesen: Engine Heat VS Power Loss. In short, keeping the bike at its optimum temperature allows the EFI system to run in the most powerful map. If the bike becomes too hot, the EFI system will slightly decrease power as a failsafe.

Long-Term Durability

This isn't actually my first go-around with the Boysen Supercooler. While our 2015 KX450F has had one for the past two months, I've also had one on another personal bike for over one year without any problems. As with any area of the engine cases though, it can be susceptible to impacts and damage caused by debris or other bikes if it doesn't have proper protection. In the case of the KX450F, the water pump is a bit exposed and could take some serious damage in certain situations. But that's true of the stocker, as well.

The Last Word

To put it simply, the Boyesen Supercooler does exactly what it's supposed to do. By increasing flow, it offers the engine the ability to run cooler and keep closer to its optimal operating temperature. This aids the engine's reliability and allows it to stay closer to its maximum power output.

Overall, it isn't a must-have product for every rider, but one that can definitely help those with a heavy throttle hand, or who live in hot climates and are experiencing cooling problems.

Vital MX Rating

For more information on Boyesen's Supercoolers, check out

About the Test Rider

Michael Lindsay- is a born-and-raised moto freak and gearhead from the heart of motocross in Southern California. First swinging a leg over a bike at the age of five, he immediately caught the racing bug, spending nearly every weekend behind a gate…and a lot of time on the couch while injured. While swinging back and forth between moto and the off-road scene, giving him a wide range of experience on the bike. Of course, all of this led to one thing: Lindsay loves working on his bikes almost as much as he loves talking about them. When he’s not in the Vital MX forum or writing his latest product review, you can find him out at the track taking dirt naps, snapping some pictures, or drooling over the latest parts for his bike. With an outspoken personality, gearhead background, and as Vital MX’s guru for product, Michael is here to share his unbiased opinion.


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Boyesen Supercooler Water Pump Kit
Heat Is the #1 Enemy of 4-Stroke Engine PerformanceBoyesen SuperCooler Water Pump Cover and Impeller Kits are specifically designed to enhance the performance of your engine's cooling system. These high-flow, hydrodynamic water pump kits have been tested and designed to flow more coolant. By increasing the flow, the engine will run cooler at a more constant temperature.The Boyesen Supercooler can reduce engine temperatures by as much as ten degrees, as confirmed by tests at Team Kawasaki. How does the Supercooler achieve this? Hydrodynamics. Boyesen's investment-cast aluminum water pump cover has bigger water inlets, a sculpted design, no casting seams, less restrictive corners, a more efficient impeller and less cavitation.Win the War on Heat, Bolt on a SuperCooler NOW!2-piece cast aluminum construction.Oil filter access for hassle-free filter changes.Increased coolant flow at all RPM ranges.Patented Nautilus style impeller for hydrodynamic efficiency.Note: Gasket(s) is NOT included; use stock piece(s) or purchase new one separately.Feature details: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.Superior Internal Hydrodynamic Shaping: Stock water pumps aren't very hydrodynamic. Their internal shape and impeller create excessive amounts of 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.Optimized Water Inlet Diameter (High Cooling Capactiy): 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).Optimized Impeller (Patented Nautilus-Style Impeller): Boyesen's patented impeller design is 25 percent more efficient at moving water than the inefficient stocker.
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