🏷️ Basic Information

Make:

KTM

Model:

125 SX / 300 SX / 125 EXC / 300 EXC

Model Variant:

SX (Motocross), EXC (Enduro)

Engine Codes:

Varies by year and specific model (e.g., 125 EXC engine codes often relate to 2-stroke single-cylinder, 300 EXC similarly)

👋 Introduction

Vehicle Segment:

High-performance Off-Road Motorcycles (Motocross and Enduro)

Brand Focus:

KTM is renowned for its 'Ready to Race' philosophy, focusing on competitive performance and advanced engineering in the off-road segment.

Competitors Sx:

Yamaha YZ125/YZ250, Honda CRF125/CRF250R, Kawasaki KX125/KX250, Suzuki RM125/RM250.

Competitors Exc:

Husqvarna TE125/TE300, GasGas EC125/EC300, Beta RR125/RR300, Sherco SE125/SE300.

Engine Type:

Lightweight, powerful two-stroke single-cylinder engines, known for their aggressive power delivery and excellent power-to-weight ratio.

Suspension:

Industry-leading WP (White Power) suspension components, offering extensive adjustability and superior performance for demanding off-road conditions.

Chassis Design:

Lightweight and robust steel trellis frame, optimized for agility and rider feedback.

Handling:

Renowned for sharp, precise handling and agility, allowing riders to navigate technical terrain with confidence.

Benefits To Owner:

Provides essential knowledge for maintaining peak performance, ensuring longevity, and performing minor repairs, enhancing the ownership experience.

📋 Manual Details

Covered Models:

KTM 125 SX, KTM 300 SX, KTM 125 EXC, KTM 300 EXC

Covered Years:

Assumed to cover a range of recent model years for both SX and EXC variants. Specific year range not explicitly stated but implied to be comprehensive for 'Complete'.

Estimated Page Count:

Typically 300-500 pages, depending on the exact year and included variants.

Manual Type:

Complete Official Owner's/User Manual

Language:

English

File Format:

PDF

📖 Manual Coverage

Engine:

Detailed diagnostics, maintenance, repair procedures, specifications for 125cc and 300cc two-stroke engines (carbureted and potentially TPI fuel injection systems depending on year).

Transmission:

Clutch operation, gearbox maintenance, troubleshooting, oil specifications, shift mechanism.

Chassis:

Frame inspection, fork suspension (WP APEX/XPLOR), rear shock absorber maintenance and adjustment, linkage systems.

Brakes:

Brake system components (hydraulic), pad replacement, fluid specifications and bleeding procedures, rotor inspection.

Electrical System:

Wiring diagrams, battery maintenance, lighting systems, ignition system troubleshooting, sensor identification.

Fuel System:

Carburetor adjustment/rebuild (if applicable), fuel injection system components (TPI), fuel filter, fuel pump operation.

Cooling System:

Radiator maintenance, coolant specifications, fan operation (if equipped).

Exhaust System:

Pipe and silencer maintenance, packing replacement.

Wheels And Tires:

Tire pressure recommendations, rim maintenance, spoke tensioning, wheel bearing service.

Routine Maintenance:

Oil changes, air filter cleaning/replacement, spark plug inspection/replacement, chain lubrication and adjustment.

Troubleshooting:

Diagnosing common starting issues, engine performance problems, electrical faults.

Repair:

Engine rebuild steps, gearbox disassembly, suspension servicing, brake caliper overhaul.

Adjustments:

Carburetor jetting, suspension sag and damping adjustments, clutch and throttle cable free play.

Special Tools:

Identification of necessary specialized tools for specific repair procedures.

Depth Of Information:

Comprehensive, covering from basic user checks to detailed mechanical repairs and diagnostics. Suitable for both owners and independent technicians.

📊 Manual Specifications

File Type:

PDF (Portable Document Format)

Searchable:

Yes (typical for professionally generated PDFs)

Zoom Functionality:

Yes

Printability:

Yes, printable

Quality Level:

Factory Quality

Binding:

N/A (Digital PDF)

Paper Quality:

N/A (Digital PDF)

⚙️ Engine Specifications

Engine Type 125:

125cc Liquid-Cooled 2-Stroke Single-Cylinder

Engine Type 300:

300cc Liquid-Cooled 2-Stroke Single-Cylinder

Bore X Stroke 125:

Typically around 54 mm x 54.5 mm (varies slightly by year)

Bore X Stroke 300:

Typically around 72 mm x 72 mm (varies slightly by year)

Compression Ratio 125:

High, generally around 12.5:1 or higher

Compression Ratio 300:

High, generally around 11.5:1 or higher

Horsepower 125:

Around 38-40 hp (stock, varies by year/tune)

Horsepower 300:

Around 50-53 hp (stock, varies by year/tune)

Torque 125:

Approx. 25-27 Nm

Torque 300:

Approx. 38-40 Nm

Carburetor 125 Exc Pre Tpi:

Keihin PWK 36/38mm (specific size depends on year)

Carburetor 300 Exc Pre Tpi:

Keihin PWK 38mm

Fuel Injection Tpi:

KTM TPI (Transfer Port Injection) 2-stroke system (introduced in later years, typically 2018 onwards for EXC models). Features twin injectors in the transfer ports.

Fuel Type:

Unleaded gasoline, minimum 95 octane (RON+MON)/2). Recommended to use high-quality fuel. Pre-mix oil ratio as specified in manual (typically 1:50 or 1:60 for auto-lube, or pre-mix for manual lubrication).

Premix Ratio Manual:

As per manual, typically 1:50 to 1:80 with high-quality 2-stroke oil for specific applications (e.g., racing).

Ignition System:

Digital CDI with dual ignition curves (selectable by rider in many models).

Cooling Method:

Liquid Cooling (Water-Cooled)

🔧 Transmission

Transmission Type:

6-Speed Constant Mesh

Optional Transmission:

N/A (Standard 6-speed for these models)

Clutch Type:

Hydraulically operated, multi-disc wet clutch (Brembo or similar quality components).

Gear Ratios:

Specific ratios vary by model year and SX/EXC designation; manual provides exact figures.

Transmission Oil Spec:

Typically SAE 10W/50 or SAE 75W API GL-4/GL-5 or specifically designated motorcycle gear oil. Manual will specify exact type and capacity.

📐 Dimensions

Frame Type:

Central double-cradle-type, 25CrMo4 steel frame

Ground Clearance:

Typically around 350-380 mm (varies by model and suspension setting)

Seat Height:

Typically around 950-970 mm (varies by model)

Dry Weight 125:

Around 95-96 kg (approx.)

Dry Weight 300:

Around 98-100 kg (approx.)

Fuel Tank Capacity:

Typically 7.0 - 9.5 liters (varies by model, EXC models usually have larger tanks)

🛡️ Safety Features

Safety Certifications:

Not typically crash-tested for road safety ratings as they are off-road vehicles. Safety features focus on rider control and mechanical integrity.

Braking System:

High-performance hydraulic disc brakes (Brembo) front and rear, with wave-style rotors for improved heat dissipation and self-cleaning.

Suspension Control:

WP suspension with extensive adjustability (compression, rebound) allows rider to fine-tune for optimal grip and stability.

Frame Integrity:

Robust steel trellis frame designed for strength and rigidity under extreme loads.

Ergonomics:

Carefully designed rider triangle and handlebar position for control and reduced fatigue.

💡 Technology Features

Infotainment System:

N/A (Designed for off-road performance, no infotainment system present).

Rider Aids:

Minimal. May include selectable engine maps on some models. EXC models might have basic lighting systems. No electronic rider aids like ABS or traction control are standard on these performance off-road models.

🔧 Maintenance

Oil Change Interval:

Every 10-15 operating hours for transmission oil, or as specified by the manual for engine oil (if separate).

Air Filter Cleaning:

Frequent cleaning recommended, typically every 5-10 operating hours, or more often in dusty conditions.

Spark Plug Inspection:

Every 10-20 operating hours, depending on plug type and usage.

Piston Ring Replacement:

Typically every 40-60 operating hours for competitive use, or 80-100 hours for recreational use. Manual will provide specific recommendations.

Top End Rebuild:

Recommended every 100-150 operating hours for optimal performance, though engines can run longer.

Engine Oil Type:

High-quality 2-stroke premix oil as specified by KTM. Transmission oil typically SAE 10W/50 or similar, meeting GL-4/GL-5 spec.

Coolant Type:

Engine coolant (ethylene glycol based) with corrosion inhibitors, typically a 50/50 mix with distilled water.

Brake Fluid Type:

DOT 4 Hydraulic Brake Fluid.

Common Wear Items:

Clutch plates, piston rings, spark plugs, air filters, wheel bearings, chain and sprockets, exhaust packing.

Ktm Specific Points:

Regularly check for chain tension, radiator hose condition, and ensure airbox seal is perfect to prevent dirt ingress. TPI models may require specific diagnostics for fuel system issues.

📚 Vehicle History

Ktm Offroad Focus:

KTM has a long and dominant history in off-road racing, including motocross and enduro. The SX and EXC lines are direct descendants of this racing heritage.

Sx Line:

The SX line represents KTM's pure motocross offerings, designed for closed-course competition with aggressive engine tuning and race-focused suspension.

Exc Line:

The EXC line is designed for enduro riding, often featuring larger fuel tanks, different gearing, lights, and more compliant suspension settings suitable for varied terrain and longer distances. Many EXC models adopted TPI fuel injection in recent years.

Manufacturing Location:

Primarily manufactured in Austria by KTM Sportmotorcycle AG.

🏆 Awards & Recognition

Racing Success:

KTM models, including the 125 and 300 SX/EXC platforms, have a long history of winning national and international championships in Motocross and Enduro disciplines.

Editorial Acclaim:

Consistently praised by motorcycle publications for their performance, handling, and build quality in the competitive off-road market.