TWO STROKE

Two stroke
Many motorcyclists over the years have been convinced that two-stroke engines were better suited to motorcycles than equivalent four-strokes: they are mechanically simple, easier to cold start, and when operating at their best produce significantly more power from lighter mechanicals, having twice as many powerstrokes at the same engine revolutions. Their fuel inefficiency seemed a smallish price to pay. However, they have been largely displaced in the larger displacements and in developed nations by their environmental disadvantages. Poorly burnt fuel and burning oil result in two-strokes being markedly less clean than four strokes.
Rotax powered snowmobile, some Auto rickshaw/tuk-tuk and most scooters engines utilize air-assisted direct injection though. Four-stroke engines are more reliable in configurations where the RPM is kept relatively low. A four-stroke powerband is of broader range than a two-stroke, making such machines easier to control. However modern two-stroke engines, or at least those powering dirt bikes, have some form of exhaust power-valve system providing a similar powerband range.
Almost all modern two-stroke bikes are single-cylinder, water-cooled, and under 500cc. In Europe there are many 125cc two-stroke street bikes and 125cc or 250cc offroad motorcycles. Most mopeds and some scooters have 50cc two-stroke engines