Description DEF Racing 2014-2019 Yamaha YZ450F high-performance 2.0mm oversize titanium exhaust valves and 3.0mm oversize titanium intake valves. We highly recommend using these valves with larger cylinder bores and a properly ported head. Primarily used for Drag racing & Hill Climb racing with the focus of delivering significant gains to top end power. Sold as a complete set of 4 valves! Product Features: Exhaust Valves: Increased diameter of 32.5mm ( 2.0mm larger than OEM) – Titanium Intake Valves: Increased diameter size of 40mm ( 3.0mm larger than OEM) – Titanium Requirements! Will require machine work to remove and reinstall larger valve seats Must use at least a 33.mm exhaust valve seat Must use at least a 40.5mm intake valve seat Requires a piston with increased valve pocket diameters! Valve Stem Size: Remain OEM of 5.5mm Material: Manufactured in the USA with high-quality titanium for exceptional strength and longevity Design: Proprietary tulip and margin shapes specifically designed to improve airflow, reduce reversion and turbulence Durability: Hours of testing and racing have proven to be extremely durable For the best results, we recommend using this valve kit with a properly ported head, larger bore and throttle body to fully unlock its potential. Related