This manual covers the Rotax 800 V 810 engine, a V-Twin, 4-stroke power unit commonly found in All-Terrain Vehicles (ATVs) from 2006. Renowned for its robust design and performance, the Rotax engine series has a strong heritage in the powersports industry. This engine, with a displacement of approximately 800cc, is engineered to deliver reliable power for demanding off-road applications, offering an expected horsepower range of 50-70 HP depending on the specific ATV model and tuning. This comprehensive service repair workshop manual provides in-depth technical information for the professional technician. It details engine mechanicals, fuel and ignition systems, cooling, lubrication, electrical systems, and exhaust systems. The manual includes procedures for routine maintenance, scheduled servicing, component inspection, diagnosis of faults, and repair procedures ranging from minor to major overhauls. Troubleshooting guides and diagnostic trees are also included to assist in identifying and resolving performance issues, starting problems, and other operational concerns.