🔍 Key Concepts

• Two-stroke cycle sequence: scavenging/intake, compression, power (expansion), and exhaust • Relationship of piston position (TDC/BDC) to crank angle on a circular diagram • Which portion of the crank angle has both valves/ports mostly closed so pressure can act on the piston

💭 Think About

• On this diagram, where would the crank be when hot, high-pressure gases are expanding and actually doing work on the piston? • Look for the segment that begins just after fuel ignition and continues until near the point where exhaust ports/valves start to open—where is that on the circle? • Which labeled segment covers the longest downward motion of the piston with ports mostly closed in a two-stroke engine?

✅ Before You Answer

• Identify TDC (top dead center) and BDC (bottom dead center) on the circular layout before choosing • Decide which labeled arc represents the expansion of burned gases between ignition and exhaust opening • Confirm that your choice matches the usual crank-angle range of the power stroke in a two-stroke (from just after TDC down toward BDC)