Moto Tassinari Yamaha YZ250 02-24 YZ250X 16-24 VForce4 Reed Valve Kit

The all-new VFORCE4X has been designed to offer you exceptional durability and overcome the shortcomings of the stock reed valve system.

The VForce4 is built upon the solid foundation that made the VForce3 reed valve system such a success for over fifteen years. While the VForce3 has been continually refined over the years (including the latest VForce3R models), this is a complete redesign of the entire system. We jokingly say, "The only thing we didn't change is the bolt pattern." However this is actually quite true.

All the components that go into making a VForce reed valve system have been significantly changed since the VForce3. The reed cage design now incorporates an airfoil shape at the reed tip area to increase air velocity from the outer ports. We use an all-new reed petal resin system, carbon fiber and lay-up on our new pre-curved reed petals. The benefit of the pre-curved reed petal is better sealing at the tip area.

The VForce4 also features longer reed stops to progressively slow petal tip velocity, for increased petal durability. The combined reed tip area has been increased by over 10% resulting in increased total airflow. Finally, we reduced frontal area of central wing by 15.6% combined with a more aerodynamic shape.

The all-new VForce4R models incorporate a rubber overmodling on the reed surface to drastically increase reed petal life, while also creating a superior sealing surface.