This manual provides comprehensive guidance for a range of engines, including the F2L, F3L, F4L, F2M, F3M, F4M, BF3L, BF4L, BF3M, and BF4M series. These engines are engineered for reliability and efficiency, suitable for various industrial and commercial applications. This document is designed to be accessible to users of all experience levels, from novice owners to seasoned professional technicians, ensuring that all necessary information is readily available to perform procedures accurately. The scope of this manual encompasses essential information for maintaining and repairing these engines. It covers detailed specifications, safety regulations, disposal guidelines, operating procedures, and workshop practices. Furthermore, it includes job cards, technical data, test and adjustment data, tightening specifications, and information on both commercial and special tools. By utilizing this manual, owners and technicians can effectively carry out routine maintenance, prevent premature component failure, and ensure the optimal performance and longevity of their engines.