A small engine is a type of internal combustion engine that typically has a displacement of less than 25 horsepower. These engines are commonly found in various equipment, such as lawn mowers, chainsaws, and generators. They are designed to be lightweight and efficient, making them suitable for portable applications. Small engines operate on a simple principle: they mix fuel and air, ignite the mixture, and convert the resulting energy into mechanical power. They can run on different types of fuel, including gasoline and propane, and are often used in outdoor power equipment and recreational vehicles like ATVs and go-karts.