🏷️ Basic Information

Make:

KTM

Model:

400 SX, 450 SX, 400 MXC, 450 MXC, 400 XC, 450 XC

Engine Codes:

LC4 (various iterations for 400cc and 450cc variants)

👋 Introduction

Category:

Competition Motorcycles (Motocross, Enduro, Cross Country)

Competitors:

Yamaha YZ/WR series, Honda CRF/XR series, Suzuki RM/DR series, Kawasaki KX/KLX series.

Vehicle Focus:

High-performance off-road machines known for their powerful engines and robust construction, designed for demanding competitive use.

📋 Manual Details

Years Covered:

2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007

Type:

Complete Workshop Service Repair Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Engine:

Complete overhaul, tuning, fuel system (carburetor), ignition system, cooling system, lubrication system, engine internals (pistons, rings, valves, camshafts, crankshaft).

Transmission:

Clutch, gearbox (gear selection, internal components), final drive (chain and sprockets).

Chassis:

Frame, subframe, swingarm, steering system, suspension (forks and rear shock absorber), wheels, tires, brakes (front and rear caliper, master cylinder, lines, pads), electrical system (wiring harness, lighting, ignition switch, starter motor, battery).

Maintenance:

Regular service intervals, oil changes, filter replacements, chain adjustment, brake fluid flush, coolant replacement, spark plug inspection/replacement, valve clearance checks.

Repair:

Complete engine rebuild, gearbox repair, suspension overhaul, brake system repair, electrical diagnostics and repair, carburetor tuning and rebuilding, bodywork repair and replacement.

Troubleshooting:

Diagnostic flowcharts, common fault identification, solutions for starting problems, running issues, electrical faults, suspension performance.

Depth:

Comprehensive, covering from basic rider maintenance to full workshop-level mechanical and electrical repairs, including detailed diagrams and specifications for complete disassembly and reassembly.

📊 Manual Specifications

Quality:

High-resolution scans, searchable text content within PDF, clear diagrams and illustrations.

Type:

Digital Download (PDF)

Type:

Not Applicable (Digital Format)

⚙️ Engine Specifications

Type:

4-stroke, Single Cylinder, LC4 engine (Liquid-cooled)

Bore X Stroke 400:

Approx. 89 mm x 63.5 mm (varies slightly by specific year/variant)

Bore X Stroke 450:

Approx. 95 mm x 63.4 mm (varies slightly by specific year/variant)

Displacement 400:

373cc - 398cc (approx.)

Displacement 450:

435cc - 449cc (approx.)

Horsepower 400:

Approx. 30-35 HP (subject to variant and tuning)

Horsepower 450:

Approx. 35-45 HP (subject to variant and tuning)

Carburetor:

Mikuni VM Series (e.g., VM33, VM34) or Keihin FCR Series (often 39mm or 41mm) depending on model and year.

Fuel Type:

Unleaded Gasoline (Octane rating specified by KTM, typically 91+)

🔧 Transmission

Type:

5-speed constant mesh sequential gearbox.

Type:

Not Applicable (standardized for competition models)

Clutch:

Wet multi-plate clutch, hydraulically actuated.

📐 Dimensions

Wheelbase:

Approx. 1450-1480 mm (varies by model and year)

Seat Height:

Approx. 950-990 mm (varies by model and year)

Dry Weight:

Approx. 110-120 kg (varies by model and year)

🛡️ Safety Features

Type:

Not Applicable (Competition Off-Road Motorcycle, not subject to road vehicle safety ratings like NHTSA or Euro NCAP).

Brakes:

Hydraulic disc brakes (front and rear) with floating calipers. Brembo components often utilized.

Frame:

High-strength steel trellis frame providing rigidity and impact absorption.

💡 Technology Features

Type:

Not Applicable (Purely focused on performance and racing, no infotainment systems).

Features:

None. These are analog, rider-controlled machines.

Features:

None.

🔧 Maintenance

Oil Change:

Every 15-20 hours of riding or as per manual recommendations (depending on severity of use).

Air Filter Cleaning:

After every riding session or as needed in dusty conditions.

Spark Plug Inspection:

Every 20-30 hours of riding.

Valve Clearance Check:

Every 30-50 hours of riding (critical for performance).

Engine Oil:

KTM recommends specific semi-synthetic or fully synthetic motorcycle engine oils (e.g., Motorex Power Synt 4T 10W/40 or 15W/50). Consult manual for precise API/JASO specifications.

Coolant:

Mixture of distilled water and a quality motorcycle coolant/antifreeze (ethylene glycol based), typically a 50/50 mix. Refer to manual for specific type and capacity.

Brake Fluid:

DOT 4 hydraulic brake fluid (for Brembo systems).

Fork Oil:

Specific suspension fork oil grade (e.g., WP Suspension recommends 5W or 7.5W, but consult manual for exact type and level).

Common Wear Items:

Clutch plates, piston rings, valve guides, wheel bearings, steering head bearings, fork seals, rear shock absorber seals, chain and sprockets.

Carburetor Tuning:

Sensitivity to altitude and temperature changes, requiring occasional jetting adjustments.

Electrical System:

Wiring harness integrity in high-vibration environments, stator and regulator/rectifier reliability (though generally robust).

📚 Vehicle History

Focus:

KTM AG, an Austrian manufacturer renowned for its off-road racing motorcycles, consistently dominating motocross and enduro championships.

Lc4 Development:

The LC4 engine platform has a long history within KTM, evolving from earlier models to incorporate liquid cooling, electric start (on some variants later), and higher performance tuning for racing applications. The SX, MXC, and XC designations represent specific off-road racing disciplines (Motocross, Marathon Cross Country, Cross Country).

Manufacturing Location:

Austria (Primary)

🏆 Awards & Recognition

Model Legacy:

KTM's SX, MXC, and XC platforms are synonymous with off-road racing success and have garnered numerous championships and accolades across various disciplines and continents.