1. Engine Systems
Parts Review

2. Engine systems
Compression
Fuel
Governor
Ignition
fuel

3. Compression system

4. Compression System Parts: Block Piston Piston Rings Cylinder head
The compression system includes all of the parts that create, contain and manage the engine compression.
Parts:
Block
Piston
Piston Rings
Cylinder head
Valves
Valve Springs
Connecting rod
Crankshaft
Gaskets
Camshaft

5. Piston Rings Compression Wiper ring Oil ring
Subject to to greatest amount of chemical corrosion & highest temp
Transfers 70% of combustion heat from piston to cylinder walls.
Wiper ring
Meters oil film on cylinder walls
Must be installed correctly.
Oil ring
Constructed of two thin rails with holes or slots cut in-between.
Has the highest pressure against the cylinder wall of the three rings.
Wiper Ring
Oil Ring

6. Fuel System

7. Fuel System Fuel system parts:
Supply (tank)
Lines
Shut off valves
Filter
Pump
Carburetor
The function of the fuel system includes:
storing
metering
atomizing
vaporizing
mixing fuel and air
delivering fuel air mixture to intake manifold
Failure in any part of the system results in an engine that is hard to start and/or will not produce rated power.

8. Vaporization
Vaporization is the process converting a liquid to a vapor.
Fuel must be vaporized because liquid fuel will not burn.
The rate and efficiency of vaporization is improved when the liquid is reduced to small droplets (atomized).
Heat

9. Carburetor

10. Governor System

11. Governor system
The function of the governor system is to maintain the desired engine speed regardless of engine load.
The governor is attached to the throttle on the carburetor and supplies a force that attempts to close the throttle.
The governor spring is attached to the governor linkage and applies a force that attempts to open the throttle.
A constant engine speed means these two forces are balanced.

12. Governor parts

13. Ignition System

14. Ignition System
The ignition system provides a high voltage spark in the combustion chamber at the proper time.
Magneto
Magneto systems must produce the current, transform the voltage and time the spark plug.
Most small engines use the magneto system

15. Magneto Ignition System Parts
Magnets
Points (Breaker point only)
Trigger coil
Conductors
Spark plug
Condenser (Breaker point only)
Lamination stack
Primary winding
Secondary winding