| Basic engine components |
The cylinder head attaches to the cylinder block. A gasket makes a seal between them. Some cylinder blocks have passages to carry oil and coolant. |
| 4 & 2-stroke engine differences |
Ports in the cylinder head or walls carry air-fuel mixture and exhaust gases. In 4-stroke engines, valves open and close the ports. A rocker arm acts on a valve spring to operate the valve. |
| Engine cams & camshaft |
A cam is a lobe on a camshaft, shaped to control how the valve opens and closes. The camshaft keeps all of the valves working with the correct timing and in the correct sequence. |
| Engine power transfer |
Power can be transferred from the crankshaft to the camshaft by
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| 2-stroke power transfer |
The crankcase is the lower part of the cylinder block. In a 2-stroke gasoline engine, air-fuel mixture flows through a transfer port from the crankcase to the combustion chamber. |
| Scavenging |
Crossflow scavenging: the inlet or transfer port is opposite the exhaust port. Loop scavenging: the inlet or transfer ports are within 90 of the exhaust ports. |
| Counter weights |
The crankshaft is the main rotating component in the engine. The crankshaft rotates in main bearings. The flywheel stores momentum during non-power strokes. |
| Piston components |
The connecting rod secures the piston to the crankshaft. The piston transfers the force produced by the combustion to the crankshaft. Piston rings make a seal between the piston and the cylinder wall. |
| Alloys | An alloy is a combination of materials to make a substance that has properties that are different from the original materials. |
