This manual covers the 400ie and 620ie models produced from 2004 to 2006. These motorcycles are characterized by their air-cooled, 4-stroke, 2-valve per cylinder, Desmodromic L-twin engines, known for their distinctive Italian engineering and performance. The Monster series, a celebrated line, offers a blend of naked sportbike styling and accessible performance, making these models ideal for both experienced riders and those new to the brand. Their robust steel Trellis frame and agile handling contribute to a rewarding riding experience, embodying a commitment to quality and rider engagement. This comprehensive Factory Service Repair Manual provides detailed information for the maintenance, troubleshooting, diagnostics, and repair of your Monster. It covers all essential systems, including engine mechanicals, fuel injection, ignition, drivetrain, chassis, and electrical components. With step-by-step instructions, hundreds of color photos, and detailed wiring diagrams, this manual is an indispensable resource for owners, independent repair shops, and technicians. It is presented in both English and Italian, ensuring broad accessibility for users.