1. Two & Four Cycle Engines page 77 Questions on pg 90
Chapter 5
Two & Four Cycle Engines
page 77
Questions on pg 90

2. Small Engine Identification
# of strokes for a cycle 2 4
rotary

3. Four Stroke Cycle Engine
Intake
Compression
Power
Exhaust

4. Intake
Intake open
Exhaust closed
Piston moves downward
Vacuum

5. Compression
Both valves closed
Piston moves up
Compression 9:1

6. Power Both valves closed Spark Ignites air/fuel mixture 14.7:1
Piston forced down

7. Exhaust Exhaust valve opens Intake valve closed Piston moves up
Pushes exhaust out

8. Valve Timing Valves must open and close at correct time Align marks
Backfire
Lack power

9. Lubrication
Splash
Pressure
Hybrid

10. Two Stroke Cycle Engine
See:

11. Variation in Design Cross-scavenged Loop-scavenged
Contoured piston head
Deflect air upward
Reed valves/rotary valves
Loop-scavenged
Flat or domed piston
Intake offset for exhaust

12. Principles of Operation
Location of parts essential

13. Intake into Crankcase Piston moves up Causes vacuum
Reed/rotary valve opens

14. Fuel Transfer Piston moves down Pressurizes crankcase Transfer port
Intake port uncovered
Air/fuel rush in

15. Ignition Power Air/fuel compressed 8:1 compression TDC-spark
BTDC-advance (warm)

16. Exhaust
Exhaust port exposed
Intake pressure in
forces exhaust out

17. Scavenging & Tuning
Proper design
Full scavenging

18. Rotary Disc Valve Engine
Intake in crankcase
No reed valve
better fuel transfer

19. Reed Valve Engine Intake directly into crankcase Flexible spring steel
Reed stop
Limits valve opening
Reed opened by atmospheric pressure
Closed seals crankcase

20. 4 Cycle VS 2 Cycle 4 cycle More power More fuel efficient No-premix
Simple design
Smaller lighter
Runs at any angle
High speeds