Boyesen Parts

Explore all factory and aftermarket dirt bike products directly engineered by Boyesen.

Technical Authority Guide Brand Engineering & Heritage Guide

Boyesen — World-Class Intake, Fuel & Cooling Dynamics

### Brand Heritage & Eyvind Boyesen's Engineering Legacy Boyesen Engineering was founded in 1972 by legendary motorcycle inventor and AMA Motorcycle Hall of Fame inductee Eyvind Boyesen in Lenhartsville, Pennsylvania. Driven by a relentless passion for fluid dynamics and two-stroke combustion mechanics, Eyvind Boyesen revolutionized off-road engine performance with the invention of the patented Boyesen Dual-Stage Reed Valve. Over the past five decades, Boyesen has secured dozens of international patents and powered more national and world motocross championships than nearly any other induction specialist in history.

From the golden two-stroke era to modern electronic fuel-injected four-stroke machines, Boyesen remains the premier authority on intake airflow velocity, crankcase atomization, and hydrodynamic engine cooling. Operating from their state-of-the-art engineering and manufacturing facility in Pennsylvania, Boyesen utilizes advanced computerized flow benches, wet-flow dyno test cells, and computational fluid dynamics (CFD) modeling to design components that maximize power delivery without sacrificing low-end tractability.

  • Rad Valve Complete Intake Systems: One-piece aerodynamic cast-aluminum intake manifolds integrated with multi-stage carbon fiber reed cages, precision-tuned for two-stroke motocross and enduro machines.
  • Supercooler High-Flow Water Pump Kits: Hydrodynamically optimized investment-cast water pump covers and precision-sculpted nautilus impellers that eliminate cavitation and lower engine operating temperatures.
  • Power Reed & Pro Series Carbon Petal Kits: Patented dual-stage replacement reed petals engineered with lightweight top petals for low-end throttle snap and stiff carbon base petals for maximum high-RPM airflow.
  • Factory Racing Clutch & Ignition Covers: Heavy-duty cast-aluminum engine covers featuring high-durability powder-coated finishes that provide superior impact resistance over fragile OEM magnesium covers.
  • QuickShot 3 Accelerator Pump Covers: Four-stroke carburetor performance covers featuring adjustable leak jets that eliminate off-idle hesitation and bogging.

### How Boyesen Components Outperform Stock OEM Standard production motorcycle engines are designed around mass-manufactured cast and molded parts with inherent aerodynamic and hydrodynamic restrictions: 1. Intake Flow Velocity & Atomization: Stock two-stroke reed cages feature flat, boxy internal walls and plastic bodies that flex under vacuum. This creates severe boundary-layer turbulence, dead air zones, and uneven fuel distribution between the upper and lower crankcase transfer ports. The Boyesen Rad Valve features continuous aerodynamic curvature (Aerodynamic Surface Optimization) cast directly into rigid aluminum, accelerating intake charge velocity and atomizing fuel droplets for instantaneous throttle response. 2. Hydrodynamic Cavitation Elimination: Modern high-RPM four-stroke race engines generate extreme thermal loads. Stock water pump covers feature sharp 90-degree internal bends, and stock flat impellers create hydrodynamic cavitation—microscopic vapor pockets that collapse and prevent coolant from contacting the hot cylinder walls. The Boyesen Supercooler utilizes smoothly contoured nautilus water channels and a curved-vane impeller that increases coolant flow rate by up to 25-30%, lowering engine temperatures by 10-15°F and eliminating horsepower fade during long motos. 3. Engine Case Armor: Factory OEM magnesium clutch and ignition covers are paper-thin and easily punctured by brake pedals or rocks. Boyesen Factory Racing covers are cast from high-density aluminum alloy and powder-coated to provide impenetrable roost protection.

### Aerospace Materials & Patent-Protected Technologies Boyesen products are manufactured entirely in the USA using proprietary materials and patented technologies. Boyesen carbon fiber reed petals are woven from aerospace-grade carbon fiber cloth pre-impregnated with high-temperature epoxy resins, delivering exceptional memory retention and fatigue resistance under millions of high-RPM flex cycles. Supercooler covers and Rad Valve bodies are investment-cast from high-silicon aluminum alloys that resist thermal warping and chemical degradation from aggressive racing coolants.

  • Reed Petal Inspection: Inspect carbon reed petals every 30-40 operating hours. Hold the Rad Valve up to a light source; if light is visible beneath the petal tips (gap exceeding 0.015 inches) or if petal edges show fraying, replace with a genuine Boyesen Pro Series reed petal kit.
  • Water Pump Maintenance: When installing a Boyesen Supercooler, always inspect the engine's mechanical water pump shaft seal for weeping. Use high-grade motorcycle coolant and burp the cooling system thoroughly before starting.
  • Engine Tuning: Because Boyesen intake components dramatically improve air velocity and fuel atomization, slight carburetor air screw or EFI fuel trim adjustments (typically 1-2% fuel trim) can be made to optimize throttle snap.

Frequently Asked Questions

Q: How does the Boyesen Rad Valve differ from plastic multi-piece reed cages?

A: The solid one-piece cast aluminum housing of the Rad Valve never warps or flexes under engine vacuum or thermal heat, ensuring an airtight seal and consistent intake velocity across all RPM ranges.

Q: Will the Supercooler water pump prevent my four-stroke from boiling over in mud races?

A: Yes. By increasing coolant flow volume by up to 25-30% and eliminating cavitation, the Supercooler keeps cylinder wall temperatures significantly lower, preventing boil-overs during slow technical riding and heavy mud motos.

Q: Can I replace just the carbon reed petals on my Rad Valve?

A: Yes. Boyesen manufactures direct-fit replacement Pro Series carbon reed petal sets that bolt directly onto your existing Rad Valve cage.