VForce4X. The all-new VForce4X has been designed to offer you exceptional durability and overcome the shortcomings of the stock reed valve system. 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+ years. The simple premise of the VForce reed valve system is to increase engine power and throttle response by increasing the efficiency over a conventional reed valve design by doubling the reed-tip surface. Designed to offer you exceptional durability and overcome the shortcomings of the stock reed valve system.