The John Deere 340 Cyclone Snowmobile, produced between 1972 and 1977, represents a significant piece of vintage recreational equipment from a manufacturer renowned for its engineering and durability. This model was part of John Deere's venture into the competitive snowmobile market during a period of rapid innovation. Designed for winter exploration and recreation, the 340 Cyclone embodies the robust construction and functional simplicity characteristic of its era, offering a reliable and capable platform for snow-bound adventures. Its legacy as a product of John Deere's established heritage in outdoor machinery underscores its potential for enduring performance and collectibility. This comprehensive service repair workshop manual provides detailed factory-level information for the John Deere 340 Cyclone Snowmobile, covering model years 1972 through 1977. It is an essential resource for owners, mechanics, and technicians, offering extensive guidance on complete factory service, repair procedures, and troubleshooting. The manual delves into all major systems, including the engine, fuel, ignition, drive, suspension, steering, braking, and electrical systems, with hundreds of detailed photos and exploded diagrams to aid in understanding. Its scope encompasses regular maintenance, diagnostics, component overhaul, and detailed repair instructions, ensuring that the 340 Cyclone can be kept in optimal working condition.