Page 48 of SuperTrapp Motorcycle Performance Exhausts Catalog by Supertrapp

46 Technology There are two primary purposes of a modern motorcycle exhaust system. The first is to manipulate how the exhaust gases exit the combustion chamber. The second is to control the sound energy (noise) generated by the combustion process. You might say that changing the appearance of the motorcycle is an important purpose of an exhaust system. While this is certainly a major reason why people choose to install aftermarket exhausts, and a major consideration when we design systems, it has little to no impact on the technology behind a well engineered system. Altering the way the exhaust gasses exit the combustion chamber can have a very significant effect on performance. You want to remove as much of the burnt fuel and air charge from the cylinder as possible before the intake valve opens. The more you can remove, the more space is available for a fresh and larger charge of new fuel. There is also a very short duration of the cam timing where the intake and exhaust valves are open at the same time. During this brief period, there is an opportunity for the exiting exhaust gases to actually pull additional raw fuel and air into the cylinder thereby increasing the total charge. This is referred to as scavenging and is accomplished by controlling the velocity at which the gasses flow through the exhaust system. There are many ways to control exhaust gas velocity. It is mostly done by using different pipe lengths, pipe diameters, expansion chambers, baffling systems, and a combination of all of them at the same time. Finding just the right combination takes a lot of effort but in the end it is well worth it. Sound is a hot topic these days. Most people mistakenly think that all of the noise comes from the exhaust. While it is a very large contributor, things such as air intakes, drive trains, cams, engine noise and even clutch levers, brake levers and foot controls add to the total vehicle noise emissions. Exhaust noise is controlled by altering the frequency of the sound through absorption techniques like packing materials and reflection techniques like baffling. At SuperTrapp, we have many tools available to properly design an exhaust system that enhances the performance of your bike. We use tuned length head pipes, stepped head pipes, mechanical baffles, louvered core materials, perforated core materials, antireversion cones, expansion chambers, absorption chambers and tuneable disc systems to name a few. Depending on the application, we select the optimum combination of these tools to create an exhaust system that will yield the best performance. Our mechanical baffle systems like those used in our Kerker designs are non-adjustable. They are designed to produce optimum results under specific conditions. To get the most benefit from your exhaust, you can choose one of our tuneable disc based systems. These give you the ability to make simple tuning adjustments to best fit your exact bike, riding conditions, and riding style. The tuneable disc system works in several ways. When stacked together, the discs form a precisely aligned gap that the exhaust exits through. The gap also functions as an approved spark arrestor. This gap is wider at the outside than the inside, which creates a pressure gradient in the exhaust stream and produces an anti-reversion effect that aids in exhaust scavenging. By adding or removing discs, you are changing the total open area that the exhaust stream flows through. This allows you to tune the power band and sound levels of your bike. Adding discs increases flow, top end horsepower, and sound. Removing discs reduces the flow and sound while increasing the bottom end torque. It may sound complicated but it is very easy to do with simple hand tools. It gives you the option to make fine adjustments to the tuning of your bike to fit your specific riding style as well as allowing the exhaust system to take advantage of additional or future bike modifications. Or, you can follow the recommendations in the instruction sheets and set it and forget it. Technology

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