Billet Proof Designs Compression Release Valves (10mm x 1.0) – Harley Pair

Designed for Harley-Davidson engines with high compression, these compression release valves from Billet Proof Designs make hot-starts significantly easier by reducing the strain on your starter motor and battery. Simply press the caps down to open the valves, crank the engine, and release—once the engine starts, the valves automatically close thanks to a consistent 5–7 Newtons of closing force. This ensures smooth operation without manual intervention.

The valves feature molded synthetic knobs that stay cool to the touch, unlike traditional machined knobs which can become uncomfortably hot during use. This makes them far more user-friendly, especially in prolonged starting scenarios. Installation requires removing the cylinder head and machining a M10 x 1.00 threaded hole adjacent to the spark plug, ensuring a secure fit for optimal performance.

Sold as a pair, these valves are compatible with Harley models requiring a 10mm x 1.0 thread pitch and offer a total length of 1-13/32 inches with 10mm of thread engagement. Their straightforward design and reliable function make them a practical solution for riders dealing with high-compression challenges.