Kibblewhite intake valves are a great upgrade from your O.E.M. motorcycle valves due to their superior performance and outstanding reliability. Black Diamond™ Valves: All KPMI Black Diamond™ stainless steel valves are impregnated by a special German process to a depth of 0.002", with a surface build up of 0.0002". This "Black Diamond™" process improves wear properties, reduces friction, and provides resistance to corrosion and wear that is superior to chrome and nickel electrolysis plating. Each valve is designed using Finite Element Analysis software, and profiles are tested on Kibblewhite's computerized flow bench. Black Diamond™ Valves are light, strong, one-piece forgings with profiles that provide excellent flow characteristics and will outlast titanium valves. White Diamond® Valves: KPMI fully CNC machines their White Diamond® Valves from a one-piece forging of either EV8 Stainless Steel or Inconel-751. These materials have proven heat and corrosion resistance properties. Each valve is designed using Finite Element Analysis software, and profiles are tested on computerized flow bench. Strict attention is paid to the surface preparation of the valves, and the purity of the chrome is closely monitored. A 360-degree anode is used to produce the highest possible grade of hard chrome finish. White Diamond® Valves are light, strong, one-piece forgings with profiles that provide excellent flow characteristics. Inconel® is classified as a "Super Alloy," meaning that it is designed to survive under the most extreme temperatures and pressures, where other valves will begin to burn, corrode, or completely fail. This is the material of choice for high output engines running turbos, superchargers, nitromethane, or nitrous. Material and workmanship for desired advantages. One-piece forged Inconel®-751 Super Alloy offers uninterrupted grain flow for head stability. High Nickel content alloy is a must for extreme exhaust gas temperatures and turbo applications. Hard Chrome Plated to provide a compatible hard surface for Inconel®. “Super-Finished” stem allows for Formula 1 level coating consistency. Dimensionally controlled production tolerances for outstanding consistency. Every surface is either CNC machined or ground as top quality valves should be. Swirl polished or CNC machined profiles are flow bench tested for optimization. Street, Strip or Track. You are choosing extreme durability and performance. Detailed Specifications: Type: Valve, intake, Black Diamond™. Material: Stainless steel. Quantity: 1. Head diameter: 1.575" / 40.00 mm. Stem diameter: 0.2750". Tulip: 23°. Overall length: 4.035". Remarks: Standard head diameter. Notes: Kibblewhite valves are sold individually. The Kibblewhite Valve Spring Kit is recommended for use with Kibblewhite valves.