Hi Depending on the models year of manufacture, theres many differences , the differences can be the compression of the engine bore and stroke whether its carb or EFI and various styling differences, digital gauges versus analog, body trim etc My Sr 50 R factory has the DiTech engine as do all all of the SR50 R factorys motorscooterguide.net/Aprilia/SR50/SR50.html www.motorscooter.com.au/html/news/aprilia/sr50/ditech.htm Take care and ride safely Yours Hank