When to Use a Resonance Chamber 

If you’ll recall from the Jurassic Park movies, the scientists claimed to have found a small piece of bone within the skull of a Velociraptor called a resonance chamber.  By passing air through the hollow bone, sound was created and hence limited communication may have been possible for these meat-eating dinosaurs.  In the ATV world the resonance chamber plays a little different function but many of the prehistoric principles remain.

Like the fossilized version of the same name, a modern resonance chamber is a hollow tubular structure designed to function with sound waves and the flow of air–specifically spent gasoline and air mixture that our engines produce through the internal combustion process.  The resonance chamber looks like a small canister attached to the head pipe of a modern four-stroke exhaust system.  We’re not aware of any quads yet coming stock with external chambers so running one at this point is limited to a few aftermarket designs.  Furthermore if the system you’re running did not come with one from the factory, it’s not an add-on modification.

How it works is a pretty simple concept in theory but complex in application.  Simplified, it provides additional storage for the pulses of hot exhaust leaving the engine.  Now let’s take a look at the complexity involved in actual operation:  In a four-stroke engine, there is a short period of time (during the fourth and final stroke) where both the intake and exhaust valve open simultaneously.  Usually, this period is so brief that what exhaust remains in the pipe is already on its way rearward and hence doesn’t affect anything.  However, there are situations (like a header with a harsh bend due to routing complications) where backpressure from unreleased exhaust can slow the engine down by jamming up the intake right at that moment of both valves being opened.

The resonating chamber is simply a space that captures sound waves within the exhaust pulse (through small bleed holes).  The dead space within forces the sound waves to cancel each other out rather then return to the backside of the exhaust valve (in the form of back pressure).  In English this means more control for the pipe builder in the struggle to optimize exhaust flow for maximum power without deafening side effects.

In your particular case, there is no way to add a resonance chamber to your existing pipe so we recommend telling your friends to read this article.