Once, the Scotsman Dugald Clerk managed to circumvent Nikolaus Otto's patent with his development of the two-stroke engine. Later, the German motorcycle and automobile manufacturer DKW successfully integrated the two-stroke engine into its two- and four-wheeled vehicles. However, its popularity, especially among cars, eventually waned due to its strong exhaust smell, high oil consumption, and emission problems. Nevertheless, two-stroke engines are still used today, not only in motorcycles but also in chainsaws and outboard motors. The standard work by H. W. Bönsch! This classic of motor literature comprehensively and thoroughly explains the functioning of the two-stroke engine. The technical fundamentals are detailed here for both beginners and professionals alike.