10×1.0mm threaded mechanical compression release valves; for most cylinder heads. Push-in the button and pressure will vent out of the valve. When the engine starts; the valves automatically close. Designedl for hard starting high compression motors. Note: MCS 978425 thread tap tool (10×1.0mm) and 978424 drill fixture tool are separately available to aid installation in Twin Cams.
JIMS, compression release valve set
€183.40
All Big Twin; XL Sportster and Buell XB models