Kibblewhite Black Diamond™ Engine Valve is a premium replacement/upgrade exhaust valve engineered for riders who demand reliable sealing, strong high-temperature durability and consistent performance from their 4-stroke valvetrain. CNC-machined from a one-piece EV8 stainless steel forging, it delivers a lightweight yet strong design with profiles built to promote excellent airflow.
This valve helps solve common valvetrain issues such as accelerated wear, friction-related power loss and corrosion damage. Thanks to a specialized German surface infusion process and a black Nitroneg-coated stem, it is built to reduce wear and friction while improving corrosion resistance—making it a smart choice for rebuilds, preventative maintenance, or performance-focused engine refreshes.
Key features:
✅ EV8 stainless steel one-piece forging CNC machined for strength and consistency
✅ Wear & corrosion resistant treatment (surface infusion depth .002 with .0002 build-up)
✅ Engineered for flow using F.E.A. and validated on a computerized flow bench
Benefits of use:
🔹 Longer service life with superior wear protection compared to chrome/nickel electroplating
🔹 Smoother operation through reduced friction and a coated valve stem
🔹 Trusted quality made in the USA and designed specifically for high-demand valvetrain use
Technical specifications:
📌 Application: Exhaust
📌 Head diameter: 31.01 mm (1.221")
📌 Stem diameter: 5.50 mm (0.2150")
📌 Length: 3.030"
📌 Tulip angle: 20°
📌 Material: Stainless Steel (EV8)
📌 Units: Each
📌 Vendor Part Number: 40-40656
Why choose this product?
⭐ Proven Black Diamond™ valvetrain design focused on durability and performance
⭐ Precision manufacturing and advanced surface treatments for demanding engine conditions
⭐ Note: Requires use of a Kibblewhite spring kit for correct setup and compatibility
