K&N Replacement XD Air Filter – YZ450F (2018–19)K&N off road replacement air filters are ideal for extended use in dirty and dusty off road riding and provide clean carburetion even at high altitude. Generally, no jet changes are required with just a K&N filter element. K&N replacement air filters are washable and reusable and provide high air flow with excellent filtration. Features: Engineered to provide increased horsepower and acceleration. Designed for quick foam or filter servicing after