Stock waterpump interiors often exhibit square-edged internal channel surfaces and sharp-edged fluid inlet passages. These imperfections are most often the result of mass production tooling limitations and are the leading cause of most stock waterpump's inability to deliver enough coolant to your engine when it is raced hard, or for long periods of time in hot and muddy conditions.

This is where the Hy-Flow Waterpump cover from Boyesen shines in comparison to your stock waterpump system.

Boyesen's Hy-Flow Waterpump cover's Opti-Form interior surfacing process eliminates all coolant flow "pinch-points" resulting in a hydrodynamically efficient interior that dramatically increases coolant flow efficiency and ultimately leads to increased fluid flow re-entry rates into your bike's engine.

Stock waterpump systems typically have relatively small intake passages which ultimately reduce their overall coolant re-entry efficiency capacity and greatly reduces internal cooling system fluid pressure. Internal fluid pressure is the most important element that affects how effective your cooling systems is at engine heat dissipation.

By using larger inlet openings, the Boyesen's Hy-Flow Waterpump covers allow your bike's coolant to re-enter into your engine faster and get to your expensive cylinder faster, ultimately making more coolant available to absorb and remove heat.

Less heat = more horsepower at the end of the moto.