🔍 Key Concepts

• exhaust back pressure and how restrictions affect gas flow • relationship between engine breathing (intake + exhaust) and power output • difference between loss of power, overheating, and overspeed (racing) symptoms

💭 Think About

• If the silencer is clogged with soot, what happens to the flow of exhaust gases trying to leave the engine? Does this make it easier or harder for the engine to push them out? • How would increased exhaust back pressure affect how much fresh air-fuel mixture can enter the cylinders on each stroke? Think about whether that would increase or decrease available power. • Which of the listed symptoms would most naturally result from the engine having difficulty getting rid of exhaust gases: cooler exhaust, valve burning, engine speeding up, or the engine feeling "choked"?

✅ Before You Answer

• Be clear on what increased exhaust back pressure does to engine performance. • Consider which option describes a common real-world symptom of a restricted exhaust system. • Eliminate choices that would normally be associated with too much air/fuel or overspeed, rather than a "choked" or restricted engine.