This manual covers the Kohler Magnum M18 and M20 Twin Cylinder Horizontal Shaft engines, designed for a variety of applications including UTVs, motorcycles, ATVs, snowmobiles, and other equipment. These internal combustion engines, available in 18 and 20 cubic inch displacements, are known for their robust construction and reliable performance. This guide is intended to provide comprehensive information for the service and repair of these versatile power units, ensuring their continued operation. The purpose of this document is to serve as a complete repair manual, offering detailed guidance on general information, routine maintenance, engine removal and installation, fuel and lubrication systems, and electrical diagnostics. It includes advanced troubleshooting procedures and parts lookup information, making it an indispensable resource for owners, mechanics, and technicians. By following the instructions within this manual, users can effectively maintain and repair their Kohler Magnum engines.