🔍 Key Concepts

• Use the Top Dead Center (TDC) degree table to see how far cylinder #9 is from its own TDC when cylinder #1 is at 0°. • Remember this is a two-stroke cycle engine, so there are only two piston strokes per crankshaft revolution: up for compression, down for power/exhaust-scavenge. • Think about what it means for a piston to be before or after TDC in terms of which stroke it is on.

💭 Think About

• From the table, note the degrees at which #1 and #9 reach TDC. When #1 is at 0°, is #9 already at TDC, past TDC, or still approaching it? • In a two-stroke engine, if a piston is some degrees before its own TDC, is it moving up on compression or down on exhaust/power? • Which of the answer choices describes the piston’s position or stroke when it is not yet at its own TDC but is close to it?

✅ Before You Answer

• Verify from the table that cylinder #9 reaches TDC at 36° referenced to #1 at 0°. • Confirm that at the instant #1 is at TDC (0°), #9 is 36° away from its own TDC and determine whether that is before or after TDC for #9. • Match that situation to the correct description: stroke direction (up vs down) and TDC vs BDC in the answer choices.