This manual covers the 125 SX, 200 SX, and ECX models produced between 1999 and 2003. These competition off-road motorcycles are renowned for their strong performance, aggressive styling, and competitive edge in motocross, reflecting a deep racing heritage. The two-stroke, single-cylinder engines, available in 125cc and 200cc variants, are liquid-cooled and feature robust construction designed for demanding off-road use. With a 6-speed manual transmission and advanced suspension systems, these models were built to excel in motocross racing environments. This comprehensive service repair workshop manual provides detailed information essential for the maintenance and repair of your 125 SX, 200 SX, or ECX. It covers critical areas including complete engine overhaul, fuel system (carburetor), ignition system, transmission, clutch, and basic chassis and electrical systems relevant to engine operation. The manual includes step-by-step procedures for routine maintenance, troubleshooting common issues, engine rebuilds, and component testing, ensuring that owners, mechanics, and technicians have the knowledge to keep these performance machines in optimal condition. 🏷️ Basic Information Identification Make: KTM Model: 125 SX / 200 SX / ECX Year: 1999-2003 Codes Engine Code Range: Likely varies by displacement and specific model year, refer to manual for precise identification Chassis Code Range: Likely varies by model year and specific SX variant, refer to manual for precise identification 👋 Introduction Market Position Category: Competition Off-Road Motorcycles (Motocross) Target User: KTM owners, mechanics, service technicians working on 125 SX, 200 SX, and ECX models from 1999-2003. Competitive Analysis Competitors Era: Competed against models from Yamaha (YZ125), Honda (CR125R), Suzuki (RM125), Kawasaki (KX125), and Husqvarna during this period. Key Features Vehicle Reputation: KTMs of this era were known for their strong performance, aggressive styling, and competitive edge in motocross. Manual Value: Provides essential, in-depth technical knowledge for maintaining and repairing these performance-oriented off-road machines. 📋 Manual Details Coverage Areas Primary Coverage: Engine (125cc and 200cc variants) Secondary Coverage: Likely includes chassis, suspension, brakes, electrical systems as they relate to engine operation and maintenance on SX and ECX models Page Count Estimated Pages: Variable, typically 300-600 pages for comprehensive service manuals of this era and scope. Specific count not provided, but expected to be extensive. Manual Type Type: Service Repair Workshop Manual Language Language: English (standard for factory service manuals of this nature) Format Format: PDF (Downloadable) 📖 Manual Coverage Systems Covered Engine Mechanical: Complete engine overhaul, cylinder head, cylinder, piston, crankshaft, connecting rod, bearings, seals, gaskets, lubrication system, cooling system (if applicable to engine). Fuel System: Carburetor specifications, adjustment, cleaning, and overhaul. Fuel lines, fuel tank maintenance. Ignition System: Ignition timing, spark plug specifications, CDI unit, stator and rotor inspection. Exhaust System: Exhaust pipe and silencer maintenance and inspection. Transmission Clutch: Clutch operation, adjustment, friction plates, pressure plates, clutch cover, gearbox inspection and maintenance. Chassis Components: Likely covers aspects related to engine mounting, frame inspection, and components directly interacting with the engine. Electrical System: Basic electrical checks related to engine starting and operation, lighting (if applicable), wiring diagrams for engine components. Procedures Included Routine Maintenance: Oil changes, filter replacement, spark plug checks, air filter cleaning/replacement, chain adjustment and lubrication. Troubleshooting: Diagnostic procedures for common engine starting, running, and performance issues. Error code explanations (if applicable). Engine Rebuild: Step-by-step instructions for complete engine disassembly, inspection, repair, and reassembly. Component Testing: Procedures for testing specific engine components such as ignition coils, carburetors, and sensors. Adjustments: Carburetor tuning, clutch lever adjustment, throttle cable adjustment. Technical Depth Depth Level: Comprehensive - covers everything from routine checks to full engine rebuilds and diagnostics. Diagnostic Tools: Likely covers basic multimeter usage and visual inspection techniques; advanced electronic diagnostic tools may not be a focus for this era's off-road bikes. 📊 Manual Specifications File Format Quality: Digital PDF, typically scanned from original factory manuals. Expect clear text and images, searchable where OCR has been applied. Printability: Designed to be printable, allowing for physical copies for workshop use. Binding Type Binding Recommendation: For printed versions, spiral binding or ring binders are recommended for lay-flat usability. Paper Type Ideal Paper Type: Glossy or semi-gloss paper is ideal for durability and image clarity if printed. ⚙️ Engine Specifications Primary Engine Type: Two-stroke, single-cylinder Displacement: 125cc and 200cc variants (specific bore/stroke figures available in manual) Cooling: Liquid-cooled (typically) Bore X Stroke: Varies by model (e.g., 125 SX approx. 54mm x 54.5mm, 200 SX approx. 64mm x 62.5mm - verify in manual) Compression Ratio: Varies by model, typically around 8.0:1 to 9.5:1 for high-performance 2-strokes (verify in manual) Performance Horsepower: Estimated 30-40+ HP depending on specific model and tuning (exact figures in manual). Torque: Specific torque figures are model-dependent and detailed within the manual. Fuel System Carburetor Type: Mikuni or Keihin (specific models like VM28, TMX38 often used - verify in manual) Fuel Type: Unleaded gasoline with appropriate octane rating, mixed with 2-stroke oil (specific ratio in manual). Premix Ratio: Typically...