We have upgraded our exhaust valve technology from a membrane bellow style actuator to a piston style actuator. A much simpler design that uses less components and eliminates bellow failure in big bore and turbocharged applications. Our piston mechanism stays lubricated by the engines 2 stroke oil sytem and is actuated by the exhaust pressure from the cylinder. Same design works well with naturally aspirated engines as well. We developed this valve design in the fall of 2010 and tested them on turbo charged, and naturally aspirated engines throughout the season with amazing results. You will love the throttle response gained. Say good-bye to failed servomotors and stretched cables. There is no need to play with cables or the reprogramming of your cdi to change the opening rpm of the valve. You can adjust the opening rpm by changing different thrust springs. Assemblies are shipped pre calibrated ready to bolt on and ride. We do stock different spring combinations for finer tuning- Kit # 78SPNG sold separately

Applications for models only 2007 thru 2011;

F8 & M8

F8 HO & M8 HO

F1000 & M1000

F1200 & M1200 BIG BORES



The valve housing is made of billet treated aluminum and valve blades made of billet high carbon heat-treated steel. We also include a plug in chip to the ecu harness that allows you to remove the servomotor without defaulting the ignition timing. Complete bolt on and ride assembly and includes tools. Overall dimensions are

2 7/16” high x 1 3/4” diameter measured from cylinder mounting surface.