The product is a complete running engine for a 2002 Yamaha Big Bear 400 2x4. The engine started right up with no smoke and shifted through the gears like it should. This engine is manufactured by Yamaha and is specifically designed for this ATV model. It includes all necessary parts and components to ensure proper function and performance, making it a reliable option for anyone looking to replace or upgrade their current engine. With this high-quality engine, users can expect smooth operation and dependable power for their Yamaha Big Bear 400.