The Thunder Flow Valve is designed to increase air flow into your air box and carburetors.
Racers and tuners as well as many trail riders have known for many years that opening up the air box in order to flow more air makes more horse power. This is usually called “ventilating” or “gutting” the air box. They also know that more air means that the engine will be running leaner exactly the same as installing a smaller main jet.
Only one thing was missing, and that was the ability to go back to the richer jetting required for colder weather or lower altitudes. What did they do about this? They tried to tape or stuff foam rubber in the openings they had created. All of this was very messy and imprecise. Much of the time they were either too rich or too lean or they had to start changing main jets in order to be jetted correctly.
There must be a better way? There is!! It’s called a Thunder Flow Valve. The TFV can be opened completely to the leanest position or closed completely to the richest position or any position in between.
The TFV gives you a range of two to four jet sizes of adjustment providing you use the recommended number of valves in your air box.
For more information on airbox modifications, read: Airbox, Friend or Foe?
The TFV “Knobby” Valve is 1 1/2″ diameter and 1 1/2″ high.
The TFV “Low-Boy” valve is a flush mounting version which is 2 5/8″ square overall.
TFV comes with black filters.
Extra filters are available in Black for Knobby and Black and Red for Low-Boy.
A cutting template is available for the Low-Boy Valves.
Technical Articles published on TFV