This Service Manual provides comprehensive guidance for the 2003 SX and EXC series of performance off-road motorcycles. These models, including the 250 SX, 400 SX, 450 SX, 520 SX, 525 SX, 250 MXC, 400 MXC, 450 MXC, 520 MXC, 525 MXC, 250 EXC, 400 EXC, 450 EXC, 520 EXC, and 525 EXC, are renowned for their Austrian engineering, powerful engines, advanced WP suspension, and agile handling. The 'Ready To Race' philosophy is evident in these machines, which were highly competitive in both motocross and enduro disciplines, known for their robust build quality and strong racing pedigree. This manual is designed to be an indispensable resource for owners, mechanics, and technicians. It covers all essential aspects of vehicle care, from routine maintenance procedures like oil changes and filter replacements to in-depth engine overhaul, gearbox disassembly, and suspension servicing. Detailed troubleshooting guides, electrical system diagnostics, fuel system adjustments, and brake system maintenance are thoroughly explained, ensuring that these high-performance motorcycles can be kept in optimal condition. The manual's extensive coverage, including high-resolution diagrams and searchable text, empowers users to effectively maintain, diagnose, and repair their motorcycles for peak performance and longevity. 🏷️ Basic Information Identification Make: KTM Model: 250 SX, 400 SX, 450 SX, 520 SX, 525 SX, 250 MXC, 400 MXC, 450 MXC, 520 MXC, 525 MXC, 250 EXC, 400 EXC, 450 EXC, 520 EXC, 525 EXC Year: 2003 Codes Manual Identifier: Service Manual 👋 Introduction Market Position Vehicle Segment: Performance Off-Road Motorcycles (Motocross and Enduro) Ktm Positioning 2003: KTM was a leading manufacturer of high-performance off-road motorcycles, known for their Austrian engineering, robust build quality, and racing pedigree. The SX and EXC lines were highly competitive in their respective classes. Competitive Analysis Competitors 2003: Yamaha YZ series, Honda CR series, Suzuki RM series, Kawasaki KX series (Motocross); Beta, Husqvarna, GasGas, TM Racing (Enduro) Key Features Manual Value Proposition: This manual provides essential, detailed information for owners and technicians to maintain, diagnose, and repair these specialized KTM off-road machines, ensuring optimal performance and longevity. Vehicle Strengths 2003: Powerful engines, advanced WP suspension, agile handling, strong performance across Motocross and Enduro disciplines. 📋 Manual Details Coverage Areas Vehicle Models Covered: KTM 250 SX, 400 SX, 450 SX, 520 SX, 525 SX, 250 MXC, 400 MXC, 450 MXC, 520 MXC, 525 MXC, 250 EXC, 400 EXC, 450 EXC, 520 EXC, 525 EXC Model Year Coverage: 2003 Page Count Estimated Pages: Over 300 pages (typical for this comprehensive manual) Manual Type Type: Full Service & Repair Manual Language Language: English Format Format: Digital (PDF) 📖 Manual Coverage Systems Covered Engine Mechanical: Engine overhaul, disassembly, assembly, tuning, valve adjustment, piston replacement, cylinder head service Engine Electrical: Ignition system, CDI unit, stator, alternator, starter motor, troubleshooting wiring diagrams Fuel System: Carburetor overhaul and adjustment (Keihin PWK/PJ), fuel pump, fuel lines, fuel tank maintenance Transmission: Clutch operation and adjustment, gearbox disassembly and assembly, shift mechanism, transmission oil specifications Suspension: Front fork (WP USD) disassembly, service, oil changes, seal replacement; rear shock absorber (WP) service and adjustments Brakes: Front and rear brake system service, hydraulic fluid replacement, caliper maintenance, pad replacement, bleeding procedures Cooling System: Radiator service, coolant replacement, hose inspection, fan operation (if applicable) Exhaust System: Exhaust pipe and muffler inspection, baffle cleaning (where applicable) Electrical Components: Lighting system, battery maintenance, fuses, wiring harness routing and repair Chassis And Frame: Frame inspection, steering head bearing service, swingarm maintenance, linkage inspection Wheels And Tires: Spoke tensioning, wheel bearing service, tire pressure recommendations, wheel balancing Procedures Included Routine Maintenance: Oil changes, filter replacements, chain adjustment, lubrication points, bolt torque checks Troubleshooting: Diagnostic procedures for common engine, electrical, and mechanical faults, fault codes interpretation (if applicable) Engine Rebuild: Complete step-by-step guides for engine disassembly, cleaning, inspection, component replacement, and reassembly Suspension Tuning: Adjustments for compression, rebound, and preload for optimal performance based on riding conditions Carburetor Tuning: Jetting recommendations, mixture screw adjustments, idle speed settings for various altitudes and temperatures Electrical System Repair: Wiring diagram analysis, component testing and replacement, headlight, taillight, and indicator troubleshooting Brake System Maintenance: Bleeding brakes, replacing brake pads and rotors, inspecting brake lines Chassis Maintenance: Steering bearing lubrication and adjustment, swingarm bearing service Technical Depth Depth: Comprehensive; covers everything from basic maintenance to full engine and gearbox rebuilds, including detailed diagnostics and specifications. 📊 Manual Specifications File Format Digital Format: PDF Searchability: Searchable text for quick information retrieval Printability: Printable pages for workshop use Print Quality Image Resolution: High-resolution images and diagrams for clarity Binding Type Digital Binding: N/A (Digital Document) Paper Type Digital Paper Type: N/A (Digital Document) ⚙️ Engine Specifications Primary Engine Engine Type: 4-Stroke Single Cylinder (SOHC/DOHC depending on specific model variant) Bore X Stroke 250: 76 mm x 54.5 mm (approx. for 250 variants) Bore X Stroke 400: 86 mm x 69.6 mm (approx. for 400 variants) Bore X Stroke 450:...