Engine Conctruction and Principles of Operation

							                              Small Engine                     Ch 8
                               Carburetion

Chapter Objectives - Upon completion of this chapter you should be able to:
       Explain theory of operation of a basic carburetor.
       I.D. and understand the function of all carburetor parts.
       Understand the effect of atmospheric pressure on the fuel
        system of a small gas engine.
       Differentiate between 3 basic types of fuel systems found
        on small gas engines.
       Perform adjustments on each carburetor type.
       I.D. & properly service the 3 types of air intake systems.
       Understand the operation & adjustment of an pneumatic
        and mechanical governor.
                         Small Engine                    Ch 8
                          Carburetion
                       Mix air & fuel to a 15:1 ratio
Carburetor Functions   Vaporize fuel
        Small Engine                      Ch 8
         Carburetion
Elevation and its effect on Atmospheric Pressure
        Small Engine                      Ch 8
         Carburetion
Elevation and its effect on Atmospheric Pressure
        Small Engine                  Ch 8
         Carburetion
Determing proper Air Fuel Ratio under load
         by sparkplug coloration


         Photo of
         Spark Plug
         Colors
Small Engine        Ch 8
 Carburetion
Venturi Principle
                  Small Engine             Ch 8
                   Carburetion
                Carburetor Draft Types




Natural Draft          Up Draft          Down Draft
 (Horizontal)
                   Small Engine                     Ch 8
                    Carburetion
                   Carburetion Fuel Systems




 Suction Type            Pump Type            Gravity Feed Type
B&S = (Vacu-jet)       B&S = (Pulsa-jet)       B&S = (Flo-jet)
      Small Engine                    Ch 8
       Carburetion
Carburetor Components and Operation
                        Small Engine   Ch 8
                         Carburetion



Carburetor Components
    and Operation
Small Engine               Ch 8
 Carburetion
Diaphragm Type fuel pump
   Small Engine                Ch 8
    Carburetion
 Types of Choking Mechanisms




Digital photos
       Small Engine        Ch 8
        Carburetion




John Deere Small Engines
   Fuel Systems video
Small Engine          Ch 8
 Carburetor
 Pneumatic Governor
Small Engine           Ch 8
 Carburetion
 Mechanical Governor
                           Small Engine                          Ch 8
                            Carburetion
                           Air Cleaner Servicing
                                Oiled Foam




Wash with liquid    Wring out in a dry   Re-oil with motor   Squeeze out all
detergent & water   towel                oil                 excess oil
Small Engine            Ch 8
 Carburetion
Air Cleaner Servicing
   Dry Element
Small Engine            Ch 8
 Carburetion
Air Cleaner Servicing
  Dual Element
                              Small Engine                     Ch 8
                               Carburetion

Chapter Objectives - Upon completion of this chapter you should be able to:
       Explain theory of operation of a basic carburetor.
       I.D. and understand the function of all carburetor parts.
       Understand the effect of atmospheric pressure on the fuel
        system of a small gas engine.
       Differentiate between 3 basic types of fuel systems found
        on small gas engines.
       Perform adjustments on each carburetor type.
       I.D. & properly service the 3 types of air intake systems.
       Understand the operation & adjustment of an pneumatic
        and mechanical governor.