Mark A.M.D 8/16/2012Backpressure is a funny topic, A lot of people talk about it without really knowing what it is or what it does. The bottom line is you want exhaust gas to flow as fast as it can through the exhaust system without it building up and causing a "backpressure". Capacity vs Velocity, 2 strokes require backpressure to bounce sound waves back toward the exhaust port to keep the air/fuel mixture from escaping in small amounts out of the exhaust, where as in a 4 stroke engine backpressure is an ENEMY. Too much will act as an exhaust brake and obviously a loss of power is endured.
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