Kibblewhite

About Kibblewhite Precision Machining (KPMI)

Kibblewhite Precision Machining, Inc. — widely known by their trademark KPMI® — is one of the motorsports world's most respected names in engine valvetrain engineering. Founded decades ago and headquartered in Pacifica, California, KPMI has spent over 80 years refining the science of valvetrain manufacturing, earning a reputation trusted by professional racers, engine builders, and everyday riders alike. Their singular focus on valvetrain technology means that every component leaving their facility is the product of deep, specialized expertise found nowhere else in the industry.

KPMI manufactures and distributes an extensive line of valvetrain components for an extraordinarily broad range of powersports applications, including Harley-Davidson motorcycles, sport bikes, dirt bikes, ATVs, UTVs, tourers, cruisers, classics, jet skis, and watercraft. Whether you are restoring a vintage British twin or building a high-output racing machine, Kibblewhite almost certainly has a solution engineered for your specific engine.

Engineering That Exceeds OEM Standards

What sets KPMI apart is their commitment to precision and material science. Their signature Black Diamond™ valves are CNC machined from one-piece forgings of EV8 stainless steel and put through a proprietary multi-stage surface treatment that reduces friction and delivers wear resistance superior to hard chrome and electrolysis nickel plating. The White Diamond® line takes things further, using one-piece forgings of either EV8 stainless steel or Inconel-751, with each valve profile designed using Finite Element Analysis software and flow-bench tested for optimization.

KPMI's engine valve springs are wound from premium Kobe Super-Clean Chrome Silicon wire, then heat-treated, stress-relieved, and shot-peened to maximize performance and service life. Springs are engineered application-by-application using proprietary simulation and analysis software, with careful attention to cam harmonics, stress, mass, and operating RPM. When combined into a complete engine valve spring kit, these components give builders a fully matched, performance-tested assembly right out of the box.

The full KPMI valve train system extends beyond just valves and springs. Bronze and cast iron valve guides, powdered metal and nickel aluminum bronze valve seats, Viton® high-temperature seals, precision retainers, tappets, and specialized tools round out a catalog of over 3,000 items — all aimed at a single industry: motorsports. For riders and builders who need a comprehensive solution, KPMI's engine exhaust / intake valve kits bundle everything needed for a professional-grade cylinder head rebuild into one convenient package.

Trusted From the Track to the Trail

KPMI's standard engine intake valves, spring kits, and valve guides are designed as direct OEM replacements that surpass factory specifications for durability and service life. Their oversize valves are purpose-built for closed-course racing applications where maximum flow and strength are critical. The brand has been trusted by top fuel drag racers, land speed record chasers, and weekend trail riders for generations — a testament to the versatility and reliability that only comes from decades of dedicated engineering.