page_title: Scooter (motorcycle)
section_title: Four-stroke engines and fuel-injection
hierarchical_section_title: Scooter (motorcycle) / Developments / Four-stroke engines and fuel-injection
caption_attribution_description: English: Aprilia SR50 R Factory, the latest model. Aprilia SR50.Aprilia SR50 Factory
context_page_description: A scooter or motor scooter is a type of motorcycle with a step-through frame and a platform for the rider's feet. Elements of scooter design were present in some of the earliest motorcycles, and scooters have been made since at least 1914. Scooter development continued in Europe and the United States between the World Wars.
  The global popularity of motor scooters dates from the post-World War II introductions of the Vespa and Lambretta models in Italy. These scooters were intended to provide economical personal transportation. The original layout is still widely used in this application. Maxi-scooters, with larger engines from 250 to 850 cc have been developed for Western markets.
  Scooters are popular for personal transportation partly due to being more affordable, easier to operate, and more convenient to park and store than a car. Licensing requirements for scooters are easier and cheaper than for cars in most parts of the world, and insurance is usually cheaper. The term motor scooter is sometimes used to avoid confusion with kick scooter, but can then be confused with motorized scooters, another distinct kind of scooter.
context_section_description: With increasingly strict environmental laws, including United States emission standards and European emission standards, more scooters are using four-stroke engines again.
   
  In 2001, Aprilia released the SR50 Ditech with direct injection. The SR50 has a listed fuel consumption of 2 litres per 100 kilometres (120 mpg‑US) and meets the Euro 3 standard with a two-stroke engine. Later on, more brands, including Derbi and Peugeot, started using direct injection systems for their scooters. Catalytic converters are now common in two-stroke and four-stroke engines sold in the E.U. and the U.S.
caption: Aprilia SR50
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