1. Principles of Engine Operation, 2 & 4 Stroke Engines
Chapter #5
23% of mowers are sold in May…
30% snow throwers are sold in December

2. Gasoline Must Be Atomized

3. Combustion Force Must Be Contained
Gas + oxygen + nitrogen in atmosphere + carbon dioxide = water + nitrogen to atmosphere (air-fuel mixture -> exhaust gases)

4. Simple engine

5. Simple Engine Operation

6. Four-Stroke Engine

7. Four-Stroke Engine
Intake Stroke

8. Four-Stroke Engine
Exhaust Stroke

9. Four-Stroke Engine
Compression

10. Four-Stroke Engine
Power Stroke

11. Four-Stroke Engine
Valve Timing

12. Four-Stroke Engine
Lubrication

13. Two-Stroke Engine
Two Design Variations
Cross-scavenge
Loop-scavenge

14. Two-Stroke Engine Principle of Operation Intake into the crankcase
Ignition-Power
Exhaust
Fuel transfer

15. Two-Stroke Engine

16. Two-Stroke Engine

17. Two-Stroke Engine

18. Two-Stroke Engine

19. Two-Stroke Engine

20. 2-Cycle Scavenging and Tuning
When properly designed the exhaust system scavenges all the exhaust gases from the combustion chamber.

21. 2 vs. 4 cycle
Textbook page 106, figure 5-17