Is Re-Jetting Required? YES
 
THESE ARE "GENUINE" MADE IN USA, BY MOTO TASSINARI. 
(NOT MADE BY CHINA OR SOLD ON EBAY)
 
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
 
 
For Application: Yamaha RD250, RD350 and RD400 (see note below)
Model Years: All
Yamaha RD250, 350 & 400 owners please note: Installing these reed valves will require modification of the intake port of the cylinders. We suggest using a Reed spacer to move reed cage further back to allow space for intake machine work to fit the cages. setting them up against the cylinder intake. Can cause over porting damage breaking out the intake side walls when releaving the intakes to fit.
you can also contact us to machine them for you if needed. 
 
RD250/RD350/RD400 owners looking for more a bolt in application can try using our YZ85 reeds for stock reed cages. you can message us for details.