Yamaha RD250, 350 & 400 owners please note: Installing these reed valves will require modification of the intake port of the cylinders. While the bolt pattern is the same, the valve will not just slide in. Material removal on the intake port walls will be required. If you do not have the ability to carry out the modifications please do not purchase the valves.

The all-new VForce4 is built upon the solid foundation that has made the VForce3 such a success for the last 10 years. While the VForce3 has been continually refined over the years, 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 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.

STANDARD VFORCE REED VALVE FEATURES
Double the reed tip surface over a conventional reed valve design
Increased bottom end, stronger mid-range and longer top-end
Greater efficiency due to reduced reed petal travel
More airflow means more horsepower
Reduced reed petal wear
Screw free design eliminates risk of screws going through motor
Screw free design enables super quick reed petal changes
NEW AND IMPROVED VFORCE4 FEATURES
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