This comprehensive service manual is specifically designed for professional technicians working on Aprilia engines, models 3AS and 4AS. It provides detailed information and step-by-step instructions for a wide range of procedures, covering everything from basic maintenance tasks to complex engine repairs. The manual includes detailed technical diagrams, specifications, troubleshooting guides, and wiring diagrams to assist technicians in diagnosing and resolving issues effectively. Whether you're a seasoned mechanic or an aspiring enthusiast, this manual provides the essential knowledge and guidance to maintain and repair your Aprilia engine with confidence.

The Aprilia 3AS and 4AS engines are a family of single-cylinder, four-stroke powerplants developed by the Italian motorcycle manufacturer Aprilia. They were primarily used in various Aprilia motorcycles, known for their sporty design and performance. These engines are renowned for their lightweight construction and compact size, making them ideal for nimble and agile motorcycles. The 3AS and 4AS engines have a displacement ranging from 125cc to 200cc, offering a balance of power and efficiency. Their relatively simple design features a single overhead camshaft (SOHC) and a single carburetor, contributing to their ease of maintenance and repair. Notable models equipped with these engines include the Aprilia RS125, a highly successful racing machine, as well as the popular street-legal Aprilia SR125 and Aprilia SR200 scooters.

The Aprilia 3AS and 4AS engines have earned a reputation for reliability and durability, thanks to their robust construction and proven design. They are known for their smooth and responsive power delivery, making them enjoyable to ride. While these engines are typically associated with entry-level motorcycles and scooters, their performance, combined with Aprilia's renowned engineering, has made them a popular choice for riders of all skill levels. Their compact size and lightweight nature further enhance the overall riding experience, contributing to the agility and handling characteristics of the motorcycles they power. The 3AS and 4AS engines offer a compelling combination of performance, reliability, and affordability, firmly establishing their place in the history of Aprilia's diverse range of motorcycles.