Breather valve BT77-99 elongated window

Jims now offers a steel replacement breather valve for Big Twin. This breather valve has an elongated rear hole to aid in better crankcase flywheel cavity vacuum. Made from the finest aerospace quality steel, and CNC machined to the highest standards. Designed to replace the stock plastic breather valve gear in all 1977-1984 Shovelhead and 1984-2000 Evolution Big Twin engines.