Two-stroke engine
The two-stroke engine is an internal combustion engine. The two strokes are:
| Stroke | Number | Piston | Intake port | Exhaust port |
|---|---|---|---|---|
| bottom dead center | open | open | ||
| compression | 1 | piston rising | closed | closed |
| top dead center | closed | closed | ||
| firing | 2 | piston descending | closed | closed |
Unlike a four-stroke engine, there are no intake and exhaust strokes. When the piston is at bottom dead center, fuel-air mixture is blown in under slight pressure. The incoming mixture forces out the exhaust gas at the same time. The animation shows an engine with crankcase compression to force in the fuel-air mixture. Some engines use a rotary blower instead. These engines use mixed fuel (often 50:1) primarily high octane gasoline, partially two-stroke oil.
Two-stroke Engine Media
Saab 96 Sport
A mini Pocketbike dirt-bike. Photograph taken by myself, en:January 16, en:2007.
Lateral view of a two-stroke Forty series British Seagull outboard engine, the serial number dates it to 1954/1955
Two-stroke motorbike with an expansion chamber exhaust system that increases the cylinder charge
A Cox Babe Bee 0.049 cu in (0.80 cm3) reed valve engine, disassembled, uses glow-plug ignition. Its mass is 64 g.
Deflector piston with cross-flow scavenging
The two-stroke cycle*Template:Ordered list** A: Intake/scavenging* B: Exhaust* C: Compression* D: Expansion (power)
The uniflow two-stroke cycle:*Template:Ordered list** A: Intake (effective scavenging, 135°–225°; necessarily symmetric about BDC; Diesel injection is usually initiated at 4° before TDC)* B: Exhaust* C: Compression* D: Expansion (power)
Two-stroke diesel uniflow engine animation
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