It’s summer time and dirt bikes everywhere are slaving away under the blistering conditions. Fortunately, aftermarket radiators can increase your bike’s performance and save you money in the long run. After being bombarded by PR material for Fluidyne Powersports radiators we finally took them up on an offer for a test unit. We rounded up some well-used machines, a 2002 Yamaha WR426F and 2009 Kawasaki KX450F, both of which were in need of some fresh cooling systems. The WR had been crashed countless times and tweaked its stock radiators enough that the hoses were pinched and it regularly blew its top in slow, technical riding. The Kawi belonged to a local pro rider who extracts a lot from his machine.
Fluidyne Powersports makes radiators for off-road, motocross and ATV machines, but its parent company has experience making high-performance cooling systems for more than just motorcycles. Fluidyne develops more than just radiators too, including oil coolers, high-output fans and transmission coolers. The company has worked successfully in the NASCAR world and a host of other top auto racing series as well as street cars and trucks. Regardless, here’s how it works on the two-wheeled side.
Compared to stock radiators, water passages are 33% wider to allow better flow, and the brazed aluminum cores are thicker which equates to 40% more surface area and up to 50% more fluid capacity. Depending on model, Fluidyne claims 10-35% better cooling. We noticed right away that the construction is very solid. TIG welds on all seams and joints and the billet filler necks have been durable and look great. The radiators come with a 16-pound cap, but a 21-pounder is available for purchase ($20).
Our initial testing took place earlier in the year when temperatures were much cooler. We took the KX-F out to the track with an inline temperature gauge installed and let the pro rider spin two laps to warm up the machine. We then sent him back out for five hard laps, after which the stock radiators registered a temperature of 170 degrees. Once it cooled we swapped over to the Fluidyne Power-Flo and did another five laps. The gauge registers 130-280 degrees and we couldn’t get the needle to move. We ran the engine at a standstill to get the peg up to 140, but after a single lap, the airflow dropped the temperature to below 130 again. We’re not sure just how low it went, but that’s at least a 40-degree difference. It was enough that the engine was barely able to reach optimum operating temperatures under the conditions we were testing under. It actually worked too well!
Top: We couldn’t get the temp gauge to even register during our initial test. Now that the outdoor temps have risen, the cooling is more appreciated. Below: The larger bottom tank contacted our aftermarket exhaust header, so watch for fitting issues if you have non-OEM parts on your bike already.
Now that summer is here, that big cooling difference is a blessing. The inline gauge was not installed on the WR, but Old Blue stopped blowing steam on every hillclimb, making the Fluidyne test a perfect 2-for-2 in our book. We did find something to complain about, however.
Fluidyne prides itself on “Direct-Fit” which means the bike won’t require any modification during installation. That wasn’t exactly the case with our machines. The KX was equipped with a Jardine RT94 exhaust system and the upper header spring contacted the lower tank on the right radiator. We had to bend the spring loop in order for it to fit. Granted, this wasn’t a stock exhaust, so we can’t argue the “Direct-Fit” on this basis. However, the WR cooling system was stock and the connecting hoses didn’t fit. The crossover tube diameter was too small and the stems on the Fluidyne radiators were too far apart. We solved this with a trip to NAPA for some auto hoses, but it was still an inconvenience.
Basically what it boils down to (pun intended) is that the Fluidyne Power-Flo radiators are bigger, beefier, increase efficiency and hold more volume. Our temperature test proves they keep your machine cooler, making life much easier on the engine during hot temperatures or hard rides. Build quality is excellent and the thicker aluminum cores have resisted crash damage much better than the soft stock units. The Fluidyne Radiators are sold individually for $250 each and the ATV systems range from $475 to $540. If you have heating issues, this is a sure bet.