2000-2007 KTM 250 EXC, 400 SX, 450 MXC, 525 SX, 610 RACING Service Manual (P/N 3.206.043-E)

• Covers the 2000–2007 KTM 250 EXC, 400 SX, 450 MXC, 525 SX, and 610 Racing engine series, including SMR, SXS, XC, and XC-W trim variants
• Official KTM publication (Art.-Nr. 3.206.043-E), updated for the 2007 model year build
• Contains 245 pages detailing factory-level technical specifications, engine disassembly and assembly workflows, exploded-view diagrams, and electrical schematics for the liquid-cooled 4-stroke architecture
• Includes the complete 2000–2007 cross-reference updating instructions for the original loose-leaf format, making it the definitive reference for the full Racing engine production run
• Documents comprehensive servicing parameters for internal components, cooling networks, and fuel systems

Engine and Maintenance Overview

Servicing these high-performance liquid-cooled single-cylinder engines requires strict adherence to factory tolerances to prevent mechanical failure and ensure safe operation. This documentation provides an in-depth breakdown of the mechanical assembly and critical maintenance parameters required for the KTM Racing series. It details the entire lubrication circuit, tracing internal oil flow paths through both long and short filters while explaining the bypass valve function. Workshop professionals will find the exact specifications needed for maintaining the hydraulic clutch system, cooling networks, and fuel delivery components. The manual also outlines rigorous verification standards for piston fitting clearances and valve train wear limits. Having this factory data on hand allows technicians to accurately assess component viability and overhaul engines to OEM standards.

Technical Specifications and Electrical Reference

Precision is everything during an engine overhaul. This reference material documents the exact torque values for critical engine fasteners and the required clearances for internal components, including crankshaft journals and conrod bearings. The cylinder head assembly table specifies a strict 0.12 mm valve clearance for both the intake and exhaust. Coolant capacity for this specific engine series is documented at approximately 0.8 liters. Beyond mechanical specs, the electrical section provides comprehensive diagnostic procedures for the KOKUSAN contactless DC-CDI ignition system. Mechanics can reference detailed tables listing primary and secondary coil resistance, stator testing protocols, and charging voltage thresholds. With the stator output confirmed at 12V 40W and specific timing values mapped out for various 4K ignition models, diagnosing complex electrical faults becomes a straightforward process rather than a guessing game.