This manual provides comprehensive technical information for 400/450 EXC, SMR, and SXS models equipped with the 400/450 LC4 engine, covering production years 2000 through 2007. These versatile motorcycles, known for their Austrian engineering and performance capabilities, are designed for a range of applications from dual-sport riding to competitive motocross and supermoto. The LC4 engine platform is celebrated for its robust torque and reliability, forming the core of these capable machines. This Service and Repair Manual is designed to be an indispensable resource for owners and technicians alike. It offers detailed coverage of engine service and repair, including complete disassembly, inspection, overhaul, and reassembly procedures for the engine core, cooling system, lubrication system, fuel system, ignition system, and exhaust system. The manual also includes routine maintenance schedules, troubleshooting guides for common issues, and step-by-step instructions for component replacement and engine rebuilds, ensuring optimal performance and longevity of your motorcycle. 🏷️ Basic Information Identification Make: KTM Model: EXC / SMR / SXS Engine Family: 400 / 450 LC4 Generation Applicable Years: 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 👋 Introduction Market Position Target Audience: Owners and mechanics of KTM 400/450 EXC, SMR, and SXS models from 2000-2007 seeking detailed engine maintenance and repair information. Competitive Analysis Value Proposition: Provides essential technical data and procedural guidance for maintaining the performance and longevity of the LC4 engine platform, crucial for these off-road and supermoto variants. Key Features Completeness: Focuses specifically on the engine, offering in-depth information often fragmented in general workshop manuals. 📋 Manual Details Coverage Areas Primary Coverage: Engine Service and Repair Page Count Estimated Pages: 300+ Manual Type Type: Service and Repair Manual Language Language: English Format Format: Digital (PDF) 📖 Manual Coverage Systems Covered Engine Mechanical: Complete disassembly, inspection, overhaul, and reassembly of the engine core (cylinder, piston, crankshaft, connecting rod, valve train). Cooling System: Radiator, water pump, hoses, thermostat, coolant specifications, bleeding procedures. Lubrication System: Oil pump, oil filter, oil passages, oil type and capacity, oil change procedures. Fuel System: Carburetor (Mikuni VM or similar variants), fuel pump, fuel lines, fuel filter, jetting specifications. Ignition System: CDI unit, ignition coil, spark plug specifications, timing procedures. Exhaust System: Exhaust pipe, muffler, heat shields, torque specifications. Procedures Included Routine Maintenance: Oil changes, filter replacements, spark plug checks, valve clearance adjustments, air filter cleaning/replacement, chain maintenance. Troubleshooting: Diagnosis of common starting issues, poor running, abnormal noises, and performance problems with detailed flowcharts and corrective actions. Engine Rebuild: Step-by-step instructions for complete engine overhaul, including torque sequences, specifications, and assembly tips. Component Replacement: Detailed guidance for replacing specific engine components like gaskets, seals, bearings, clutch components, and timing chain. Technical Depth Depth: Comprehensive diagnostic procedures, detailed technical specifications, and step-by-step repair instructions for both novice and experienced mechanics. 📊 Manual Specifications File Format Quality: High-resolution PDF with searchable text for easy navigation. Print Quality Printability: Designed for clear printing of individual pages or entire sections. Binding Type Binding: N/A (Digital Format) Paper Type Paper Type: N/A (Digital Format) ⚙️ Engine Specifications Primary Engine Engine Type: Four-stroke, single-cylinder, liquid-cooled (LC4 designation) Displacement 400: Approx. 398cc Displacement 450: Approx. 449cc Bore X Stroke Typical: Varies by specific model year and displacement (e.g., 95mm x 62.4mm for 400, 97mm x 60.8mm for 450 - *specific values detailed in manual*). Compression Ratio Typical: Approx. 11.5:1 to 12.5:1 - *specific values detailed in manual*. Performance Horsepower Estimated: 35-45 HP (Varies by model year and tuning) Torque Estimated: 30-38 lb-ft (Varies by model year and tuning) Fuel System Carburetor Model Typical: Mikuni VM40 or similar, Keihin FCR variants in later models. Fuel Type: Unleaded gasoline, 91-98 octane recommended. Valvetrain Type: SOHC (Single Overhead Camshaft), 4 valves per cylinder. Valve Clearance Intake: 0.05 - 0.10 mm (typical cold setting - *exact values in manual*). Valve Clearance Exhaust: 0.10 - 0.15 mm (typical cold setting - *exact values in manual*). 🔧 Transmission Standard Type: Constant mesh, sequential, 6-speed gearbox. Optional Features: Hydraulically actuated clutch for smooth engagement. Features Clutch Type: Wet multi-plate clutch. Transmission Oil Type: SAE 10W/40 or 15W/50 API SG, JASO MA certified motorcycle oil. Transmission Oil Capacity: Approx. 1.0 - 1.2 liters (refer to specific model year for exact capacity). 📐 Dimensions Exterior Bike Type: Dual-sport (EXC), Supermoto (SMR), Competition Motocross (SXS) - *dimensions vary significantly across these models.* Weights Dry Weight Typical: Approx. 115-135 kg (Varies by model configuration) 🛡️ Safety Features Ratings Safety Certification: Off-road and competition use focused; road legal variants may require separate homologation. 💡 Technology Features Infotainment Features: N/A (Primarily focused on performance and off-road capability, typically no infotainment systems). Driver Assistance Features: N/A (Vehicle systems are mechanically driven). Connectivity Features: N/A (No electronic connectivity features). 🔧 Maintenance Service Intervals Oil Change: Every 15-30 operating hours or 1000-2000 km (refer to specific model recommendations and usage). Air Filter Cleaning: Every 5-10 operating hours...