Aprilia SR50
The Aprilia SR50 is a sport scooter built by Italian motorbike company, Aprilia. Considered to be the first "sport" scooter, the technology used on Aprilia's SR50 have evolved throughout the years, though it has consistently used a 2-stroke 50cc displacement engine.
It features liquid cooling, 190mm front and optional rear disc brakes, 13 inch wheels, and electronic ignition. Dry weight is 198 lbs. (90 kg), a featherweight for its size and performance. It is faster and more agile compared to other scooters, consistent with its "sport" marketing. Sales of the SR50 have reached over 800,000 units already, offsetting the idea that two cycle motorcycles are fading away. Though the motor is a two cycle, it still conforms to future EURO 3 emission standards.
When modified with aftermarket parts, it can achieve speeds (on flat land) up to 70mph, while still running its original engine. That can be done by changing the carburetor jet, having the engine de-restricted and having a race-pipe (race exhaust) fitted, or other simple modifications.
Laws vary from country to country regarding licensing and operation of 50cc scooters and mopeds.
SR50 in Europe
Whilst commonly known as a Scooter (motorcycle), its power output is too high, so it is classified as a motorcycle under UK road laws. Due to recent laws (in the UK), restrictions have been added to stop people using these for racing. These restrictions include: restricting the variator (gears), restricting the carburettor, placing a restrictor bar across the bottom of the engine (to stop the installation of racing exhausts).
A de-restriction takes about 45 minutes to do using the right tools, or you can have it done at a garage (mechanics) usually for about £30–£40 each.
The SR50 ‘DiTech’ model, which costs £300 more than the carburettor version, uses an injection engine. DiTech is merely the name Aprilia gives to this engine, which is actual engineered and designed by Orbital. It is highly fuel efficient, achieving up to 120 miles per gallon.
SR50 in North America
In North America, the SR50 is considered a limited motorcycle as it has 50cc displacement and an automatic transmission. A motorcycle license is usually not required (though state and provincial laws vary) and can be registered/licensed/insured without a motorcycle license.
To sell these vehicles as mopeds, the bikes are mechanically restricted when imported to approximately 48 km/h. However, the restrictions are easily removed using simple hand tools and a software programmer available at the dealership. Once de-restricted, top speed is 95 - 105 km/h. These speeds technically require a motorcycle license, however these are laws that are rarely enforced. Modifying the engine by enlarging the cylinder bore to anything greater the 50cc also technically requires a motorcycle license, but again this is something that is difficult to detect and seldom enforced.
Although there are several variant models of the SR50 worldwide, certain models are not available in certain parts of the world: the carburetor model was available just on a few models in the first few years of the SR50 since being introduced to North America. The large majority of North American SR50s are equipped with DiTech fuel injection, with models up to 2008 using the Aprilia engine and 2009 and later models using the Piaggio engine.