Small Engine Small Engine Parts IdentificationParts Identification
Fuel TankFuel Tank
-Holds the fuel for engine consumption-Holds the fuel for engine consumption-Sometimes houses Carburetor-Sometimes houses Carburetor-Usually has a shut off valve-Usually has a shut off valve-Can house a screen that can become -Can house a screen that can become
impermeable due to varnish or trashimpermeable due to varnish or trash
Air CleanerAir Cleaner
Separates debris from air taken in during Separates debris from air taken in during operationoperation
Does NOT separate water!Does NOT separate water! Affects engine performance & lifeAffects engine performance & life Most cost effective service part found on any Most cost effective service part found on any
engineengine May use a pre-cleanerMay use a pre-cleaner Various shapes and sizesVarious shapes and sizes Constructed of many different materialsConstructed of many different materials
CarburetorCarburetor
Mixes fuel with air to provide a combustible gasMixes fuel with air to provide a combustible gas Depending on specific application a carburetor Depending on specific application a carburetor
may be Up-draft, Down-draft, or Side-draftmay be Up-draft, Down-draft, or Side-draft Can be found on fuel tank, but….Can be found on fuel tank, but…. Will always be fixed to an intake manifold that is Will always be fixed to an intake manifold that is
fixed to the cylinder head or blockfixed to the cylinder head or block May have multiple jets or “barrels” that regulate May have multiple jets or “barrels” that regulate
fuel consumptionfuel consumption Will have either manual or electric chokeWill have either manual or electric choke
Spark PlugSpark Plug
Part of the ignition system that Part of the ignition system that provides a “spark” to ignite fuel/air provides a “spark” to ignite fuel/air mixture during powerstrokemixture during powerstroke
Commonly misunderstood and Commonly misunderstood and misdiagnosed partmisdiagnosed part
Comes in many lengths and heat Comes in many lengths and heat rangesranges
Not all spark plugs are created equalNot all spark plugs are created equal
ArmatureArmature(Coil)(Coil)
Induces an electric current when Induces an electric current when rotated around a magnetic fieldrotated around a magnetic field
Always mounted in respect to Always mounted in respect to flywheel locationflywheel location
Common ignition source of choice for Common ignition source of choice for newer carbureted enginesnewer carbureted engines
Replaced breaker points ignitionReplaced breaker points ignition
Combustion ChamberCombustion Chamber
Volume of the cylinder above the Volume of the cylinder above the piston in which combustion takes piston in which combustion takes placeplace
Located mainly in the cylinder headLocated mainly in the cylinder head
CamshaftCamshaft
Shaft containing lobe (cams) that Shaft containing lobe (cams) that open and close valves as the shaft open and close valves as the shaft rotatesrotates
Controls engine timing (advance, Controls engine timing (advance, Retard)Retard)
Rotates in conjunction with the Rotates in conjunction with the crankshaftcrankshaft
Connecting RodConnecting Rod
Rod that connects the piston to the Rod that connects the piston to the crankshaftcrankshaft
Large end – crank end (end w/bolts)Large end – crank end (end w/bolts) Small end – piston endSmall end – piston end Attaches to piston via the wristpin Attaches to piston via the wristpin
CrankcaseCrankcase
Housing for the crank, cam, etc.Housing for the crank, cam, etc. Base of the engineBase of the engine Contains engine oilContains engine oil Seal housingSeal housing
CrankshaftCrankshaft
Main shaft of the engineMain shaft of the engine Provides the reciprocating motion of Provides the reciprocating motion of
the pistonthe piston Outputs rotary motion to be used to Outputs rotary motion to be used to
do work (ie. Turn pulleys, blades, do work (ie. Turn pulleys, blades, etc.)etc.)
Cylinder BlockCylinder Block
The bore in which the piston ridesThe bore in which the piston rides Usually made into the crankcaseUsually made into the crankcase Generally the largest engine Generally the largest engine
componentcomponent
Cylinder HeadCylinder Head
Detachable portion of the engine that Detachable portion of the engine that houses the combustion chamberhouses the combustion chamber
Can house valve components (OHV Can house valve components (OHV engines)engines)
Always houses spark plug(s)Always houses spark plug(s)
Exhaust ValveExhaust Valve
Valve that permits exhaust to leave Valve that permits exhaust to leave combustion chamber on exhaust combustion chamber on exhaust strokestroke
Always the smaller of the two valves Always the smaller of the two valves (int, ex)(int, ex)
Intake ValveIntake Valve
Valve that permits air/fuel mixture to Valve that permits air/fuel mixture to enter the combustion chamber on enter the combustion chamber on intake stroke intake stroke
Always the larger of the two valves Always the larger of the two valves (int.,ex)(int.,ex)
PistonPiston
Cylindrical part with closed surface Cylindrical part with closed surface area on one end connected to the area on one end connected to the crankshaft via the connecting rodcrankshaft via the connecting rod
Forces fuel/air mixture into Forces fuel/air mixture into combustion chamber combustion chamber
Exerts force back down to the Exerts force back down to the crankshaft crankshaft
Piston HeadPiston Head
Part of the piston above the rings Part of the piston above the rings Can be flat , domed , or dishedCan be flat , domed , or dished
Piston RingsPiston Rings
Expanding rings placed in the Expanding rings placed in the grooves of pistons to create a seal grooves of pistons to create a seal that keeps oil down and the fuel/air that keeps oil down and the fuel/air mixture upmixture up
Never align the open ends when Never align the open ends when installing ringsinstalling rings
Ring types- compression & Ring types- compression &
oiloil
FlywheelFlywheel
Wheel bolted to one end of the Wheel bolted to one end of the crankshaft that maintains the speed crankshaft that maintains the speed of the engine during operationof the engine during operation
Sometimes used for engine balanceSometimes used for engine balance Either used on work-end of the Either used on work-end of the
crankshaft or the free-endcrankshaft or the free-end
Flywheel KeyFlywheel Key
Used to keep the flywheel in placeUsed to keep the flywheel in place Also used as a breaker point in some Also used as a breaker point in some
ignition systemsignition systems
Oil Filler PlugOil Filler Plug
Used for both filling & checking Used for both filling & checking engine oilengine oil
Always locate this plug before doing Always locate this plug before doing anything to any engineanything to any engine
Service life begins Here!Service life begins Here!