The Small Gas Engines textbook covers all areas of engine theory and service. The book includes extensive information on L-head, overhead valve, and overhead cam engine designs. The troubleshooting and engine service information in the book is generalized rather than manufacturer-specific so that it can be applied to a wide range of engine designs from different manufacturers. The book contains all of the service procedures needed to completely rebuild a small, single-cylinder gas engine. The theory sections of the book give the reader a sound understanding of the science involved in four-stroke and two-stroke internal combustion cycles in easy-to-understand language. They also provide the reader with clear explanations of the role of basic engine components, the benefits and operation of various engine designs, and up-to-date emission control information. Review questions at the end of each chapter reinforce the important information presented in that chapter. The suggested activities at the end of each chapter are hands on and research activities that help the students apply what they have learned in the text and expand their knowledge.