Four- Stroke Four- Stroke Small EnginesSmall Engines

Transportation Transportation

Mr. OMr. O

ComponentsComponents

Recoil Start-Recoil Start- Pull start system, connects to Pull start system, connects to flywheel/crankshaft.flywheel/crankshaft.

FlywheelFlywheel- Large wheel mounted to - Large wheel mounted to crankshaft, stores momentum to keep crankshaft, stores momentum to keep engine running. Contains magnetoengine running. Contains magneto

Components (cont’d)Components (cont’d)

CrankshaftCrankshaft- Transfers piston motion into - Transfers piston motion into rotation. Used as engine output.rotation. Used as engine output.

Components (cont’d)Components (cont’d)

PistonPiston-creates combustion-creates combustionInside chamber.Inside chamber.

Piston ringsPiston rings -add compression/ -add compression/clean cylinder walls.clean cylinder walls.

*Connecting Rod-*Connecting Rod-Connects piston toConnects piston toCrankshaft.Crankshaft.

Components (cont’d)Components (cont’d)

Camshaft-Camshaft- rotate to open rotate to open

and close valves.and close valves.

Timing gear-Timing gear- Spin to control Spin to control opening/closing of valves.opening/closing of valves.

Components (cont’d)Components (cont’d)

Intake valve-Intake valve- opens opens

and closes to allow air and closes to allow air

fuel mixture to enter.fuel mixture to enter.

Exhaust valve-Exhaust valve- opens opens

and closes to allow and closes to allow

exhaust to escape.exhaust to escape.

Components (cont’d)Components (cont’d)

Sparkplug-Sparkplug- fits into cylinder head and ignites fits into cylinder head and ignites compressed fuel/air mixture.compressed fuel/air mixture.

Magneto- Magneto- device which device which

generates electric generates electric

current when rotated. current when rotated.

Coil- Coil- (ignition coil) converts low voltage into high (ignition coil) converts low voltage into high voltage needed for spark plug.voltage needed for spark plug.

Components (cont’d)Components (cont’d)

Fuel Tank- Stores gasolineFuel Tank- Stores gasoline

Air cleaner- Connects to Air cleaner- Connects to carburetor, cleans carburetor, cleans incoming air.incoming air.

Carburetor- regulates fuel Carburetor- regulates fuel intake and fuel air mixture.intake and fuel air mixture.

How 4 strokes work:How 4 strokes work: