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1985-2004 KX500 “phi” HV Impeller and gasket set combo


The OptiFlosm KX500″phi” HV Impeller, another must-have item KX500 engine.

There are only 3 ways to add extra cooling to your KX500-

1- Bigger frontal radiator area. Not going to happen in the confines of the KX500 radiator shrouds and thicker radiators only slightly delay the inevitable

2- Cooler air going through the radiator. Strictly subject to the air temperature your riding in.

3- More Coolant Flow. This is where MSV Racing’s “phi” High Volume Impeller works its magic!

Rigorous flow bench and real-world MX race testing validated the MSV Racing’s “phi” impeller performance.  Machined from 7075 T6-511 Aluminum for durability and stress resistance, the “phi” impeller dramatically improves your KX500’s H2O cooling and pumping performance over OEM, Frank’s MX, and AS3 impellers, totally dominating the competition!

The KX500 “phi” impeller vanes are computer designed using “Golden Ratio” proportions based on the KX500’s H2O pump housing. This as well as closer tolerances between impeller and housing offer +1.2  average GPM more coolant flow. This increase in flow reduces the cycle time between the engine and the radiators allowing more heat removal quicker, lowering head and coolant temperatures up to 18*f when you need it most!

Remember, horsepower/RPM = heat. Preventing your engine from heat soak is the KEY to building and maintaining maximum engine performance. The more efficient the engine’s cooling system, the more heat (horsepower) it can handle.

Whether you’re racing Outlaw Karts, GNCC, Hill Climb, Sand Drags, SuperMoto, or MX. Railing tight single track, sand dunes or just love the latest enhancement for your KX500. Trust MSV Racing’s “phi” Impeller to help put you at the head of the pack!

(Look at the pics and check out the data. No other KX500 parts company will show you the proof they are the best. It’s the MSV Racing way!)

(Mino, Frank’s MX and AS3 are the SAME over-sized impeller with spacer)

Note* To ensure ease of installation each impeller comes with an H2O pump cover gasket set for a seamless install.

Additional information

Weight .050 lbs
Dimensions 4 × 4 × 4 in



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Natural Aluminum


5054 T651 Aluminum


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