The S&S CYCLE Precision Valvetrain Component is a single‑piece crankcase breather valve engineered for the Evolution Big Twin models from 1993 to 1999. Finished in a durable silver coating, the valve features a standard diameter thread that matches the original factory specification, ensuring a seamless fit with existing valvetrain and cylinder head assemblies. Designed for street‑style riding, the component is available in several configurations—including REED VALVE, VALVE,INT 1.95" 66‑84BT, VALVE,EXH 1.72" 66‑84BT, and BALL O.P.CHK VALVE—allowing riders to select the exact valve type required for their specific engine setup.
Each unit is sold individually, making it straightforward to replace a worn or damaged breather without the need for a complete valvetrain overhaul. The precision machining of the valve ensures reliable pressure regulation and prevents oil contamination of the crankcase, contributing to consistent engine performance and longevity. By adhering to the OEM specifications, this component provides a reliable, factory‑grade solution for riders seeking to maintain or restore the original breathing characteristics of their Evolution Big Twin.