2. Spark plug Inlet valve Exhaust valve CylinderPiston The four-stroke engine

3. Inlet valve open INDUCTION STROKE The four-stroke engine

4. Inlet valve open Piston down INDUCTION STROKE The four-stroke engine

5. Inlet valve open Piston down INDUCTION STROKE The four-stroke engine Fuel in

6. Inlet valve open Piston down INDUCTION STROKE The four-stroke engine Fuel in

7. Inlet valve open Fuel in The four-stroke engine INDUCTION STROKE

8. Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up

9. Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up

10. Inlet valve closed COMPRESSION STROKE The four-stroke engine Piston up

11. Inlet valve closed POWER STROKE The four-stroke engine BANG

12. Inlet valve closed POWER STROKE The four-stroke engine Piston down powerfully

13. Inlet valve closed POWER STROKE The four-stroke engine Piston down powerfully

14. Inlet valve closed POWER STROKE The four-stroke engine

15. Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve open

16. Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve open Piston up Exhaust gases out

17. Inlet valve closed EXHAUST STROKE The four-stroke engine Exhaust valve open Piston up Exhaust gases out

18. Inlet valve open INDUCTION STROKE The four-stroke engine Exhaust valve closed

19. And so the cycle continues!!