A two-stroke engine has only three main moving parts – the piston, the connecting rod and the crankshaft. While the four-cycle engine requires four steps to produce power, the two-stroke engine only needs two. As far as repairs are concerned, faulty two-stroke engines are much easier to fix.

The two-stroke engine runs on a mixture of oil and petrol, so oil is added to the fuel before refuelling. The oil in the fuel is used to lubricate bearings in the crankcase and the piston in the cylinder. The air-fuel mixture in the combustion chamber is compressed on the first stroke by the upward movement of the piston and made to explode by the spark produced by the spark plug. At the same time, new air-fuel mixture is sucked into the crankcase via the inlet membrane through the upward movement of the piston.

The explosion forces the piston downwards on the second stroke. Burnt gases escape through the outlet port into the exhaust system. Fresh mixture is pre-compressed in the crankcase and forced into the combustion chamber via transfer ports.

Unlike the four stroke engine, the two-stroke engine does not utilise inlet/exhaust valves, as both these functions are controlled solely by the piston.