Yamaha YZ250 YZ250X 1997 2025 Moto Tassinari VForce4X Reed Valve Kit V4X07EM

  
100% Genuine Moto Tassinari Product! The VForce reed valve system by Moto Tassinari has been the reed valve system of choice by anyone serious about two-stroke engine performance for the last 25+ yrs.

The simple premise of the VForce3 reed valve system is to increase engine power and throttle response by increasing the efficiency over a conventional reed valve design. The all-new VFORCE4X for the Yamaha YZ250 and YZ250X motorcycles has been designed to offer you exceptional durability and overcome the shortcomings of the stock reed valve system. The unique design of the VForce reed valve system features double the reed tip surface over a conventional reed valve design. This has two major benefits. 1 The reed petals only travel half the distance as a conventional reed valve design to get the same airflow.

2 Because the reed petals only need to travel half the distance of that on a conventional reed valve design, there is a greater chance of them being fully opened as well as a better chance of sealing when they are "closed". A reed petal never truly "closes" in a classic sense, as it is always in movement. Consider this, an engine operating at 8,000 RPM results in a reed petal opening and closing 133 times in one second. This fact, sheds light on another VForce advantage. Since the petals are only traveling half the distance, they generally last longer as they receive less wear than the reed petals on a conventional reed valve design.

All-new reed petal resin system, carbon fiber and lay-up. Pre-curved reed petal ensures better seal at tip. Wider reed cage for maximum airflow.

Combined reed tip area increased by 10.5% resulting in increased total air flow. Airfoil shape added to cage tip to increase air velocity from outer ports. Long reed stops added to progressively slow petal tip velocity, for increased petal durability. Reduced frontal area of central wing by 15.6% combined with a more aerodynamic shape.