KTM 350 SX-F 2021 User Manual (English)

Questions and Answers:

A
Amanda PopeAug 3, 2025
What to do if my KTM Motorcycle engine does not turn when the start button is pressed?
- E
  Emily GonzalezAug 3, 2025
  If your KTM Motorcycle engine doesn't turn over when you press the start button, there could be several reasons. It could be due to an operating error, so make sure you are following the correct start procedure. The 12V battery might be discharged, so you should charge it, check the charging voltage, open-circuit current, and the alternator's stator winding. Also, the main fuse could be blown, in which case you should change it. Finally, the starter relay or the starter motor itself could be defective, so these should be checked.
C
carrie30Aug 7, 2025
What to do if my KTM 350 SX-F 2021 engine turns but does not start?
- F
  fspencerAug 7, 2025
  If your KTM Motorcycle engine turns but doesn't start, several factors could be the cause. First, check if the quick release coupling is properly joined. A clogged fuel screen in the quick release coupling could also be the problem, so you may need to replace it. Incorrect idle speed can prevent starting, so adjust it accordingly. Also, inspect the spark plug; if it's oily or wet, clean and dry it, or replace it if needed. Ensure the spark plug gap is correct, with a guideline of 0.8 mm (0.031 in). A frayed short-circuit cable or faulty switch-off button can cause this issue, so check the wiring harness and electrical system. Lastly, a malfunction in the electronic fuel injection could be the cause, requiring you to read out the fault memory using the KTM diagnostics tool.
H
Harry MunozAug 12, 2025
Why is my KTM 350 SX-F 2021 consuming so much oil?
- K
  Keith MarshallAug 12, 2025
  High oil consumption in your KTM Motorcycle can be attributed to several factors. A bent engine vent hose can cause increased oil usage, so ensure the vent hose is routed without bends, or replace it if necessary. An excessively high engine oil level can also lead to higher consumption, so check and correct the engine oil level. Using engine oil that is too thin (low viscosity) can also contribute to this issue, so change the engine oil and oil filter, and clean the oil screen. Lastly, worn piston or cylinder components can increase oil consumption, so measure the piston/cylinder mounting clearance.
P
Philip DavisAug 16, 2025
Why does my KTM Motorcycle engine overheat?
- N
  nathannorrisAug 16, 2025
  Your KTM Motorcycle engine might be overheating due to several reasons. There might be too little coolant in the cooling system, so check for leaks and verify the coolant level. Insufficient airflow can also cause overheating, so switch off the engine when standing. Dirty radiator fins can restrict cooling, so clean them. Foam formation in the cooling system can also lead to overheating, so drain and refill the coolant. Finally, a bent radiator hose can restrict coolant flow, so replace it if necessary.
J
John MartinezAug 20, 2025
Why does my KTM 350 SX-F 2021 Motorcycle have too little power?
- J
  Jeremy WilliamsAug 20, 2025
  If your KTM Motorcycle has too little power, several issues could be responsible. A very dirty air filter can restrict airflow, so clean the air filter and air filter box. A dirty fuel filter can also reduce power, so replace it. A malfunction in the electronic fuel injection could be the cause, requiring you to read out the fault memory using the KTM diagnostics tool. Check the exhaust system for leaks or deformation, and consider changing the glass fiber yarn filling in the main silencer. Lastly, insufficient valve clearance can affect power, so adjust the valve clearance.
M
Mark VargasAug 25, 2025
What to do if the malfunction indicator lamp lights up on my KTM 350 SX-F 2021?
- I
  istoneAug 25, 2025
  If the malfunction indicator lamp lights up or flashes on your KTM Motorcycle, it indicates an error in the electronic fuel injection. Check the wiring for damage and the electrical plug-in connections for corrosion and damage. You should also read out the fault memory using the KTM diagnostics tool.
D
Dominique DorseyAug 29, 2025
What to do if my KTM 350 SX-F 2021 12 V battery discharged?
- C
  Cathy HebertAug 29, 2025
  If your KTM Motorcycle 12 V battery is discharged, it could be due to a couple of reasons. The battery might not be charging, so check the charging voltage and the stator winding of the alternator. Alternatively, there might be an unwanted power consumer draining the battery, so check the open-circuit current.

KTM 350 SX-F 2021 Specifications

General

Displacement	349.7 cc
Bore x Stroke	88 mm x 57.5 mm
Transmission	5-speed
Seat Height	950 mm
Ignition	Keihin EMS
Final Drive	Chain
Front Suspension	WP XACT-USD, Ø 48 mm
Rear Suspension	WP XACT Monoshock with Linkage
Starter	Electric starter
Ground Clearance	370 mm
Engine Type	Single Cylinder, 4-Stroke Engine
Fuel System	Electronic fuel injection
Cooling System	Liquid-cooled
Front Brake	Disc brake, Ø 260 mm
Rear Brake	Disc brake, Ø 220 mm
Tank Capacity	7 liters
Frame Type	Chromium-molybdenum frame

Summary

Dear KTM Customer

Vehicle Serial Numbers

Section to enter vehicle identification and engine numbers.

Manual Disclaimer and Copyright

Notes on manual validity, specifications, and copyright.

Valid Models

Lists the specific KTM motorcycle models covered by this manual.

Means of Representation

Symbols Used

Explains the meaning of various symbols used in the manual.

Typographical Formats Used

Explains typographical formats like proprietary names and underlined terms.

Safety Advice

Intended Use Definition

Defines the intended use of the motorcycle for racing and offroad.

Misuse of the Vehicle

Explains what constitutes misuse and the associated dangers.

General Safety Instructions

Emphasizes following safety instructions and warns against removing labels.

Risk Levels and Symbols

Explains the different degrees of risk (Danger, Warning, Caution, Note) and their symbols.

Tampering Warning

Warns against tampering with the noise control system and lists prohibited acts.

Safe Operation Guidelines

Provides warnings on rider fitness, alcohol, drugs, and exhaust gas poisoning.

Protective Clothing Requirements

Stresses the importance of wearing appropriate protective clothing.

Workshop Rules and Procedures

Outlines rules for performing work on the vehicle, including tool usage and parts.

Environmental Protection

Advises on responsible use and disposal of fluids and components.

Owner's Manual Guidance

Emphasizes reading the manual for operation, handling, and service information.

Important Notes

Manufacturer Warranty Terms

Details warranty conditions, service requirements, and voiding conditions.

Fuel and Auxiliary Substances

Provides notes on fuel use, environmental hazards, and specifications.

Spare Parts and Accessories

Advises on using approved parts and installation by authorized workshops.

Service and Maintenance

Stresses the importance of proper service for operation and wear prevention.

Information on Figures

Notes that figures may show special equipment and might be simplified.

Customer Service Information

Directs users to authorized KTM dealers for questions and information.

View of Vehicle Components

Front Left View of Vehicle

Illustrates and labels components visible from the front left side.

Rear Right View of Vehicle

Illustrates and labels components visible from the rear right side.

Vehicle Identification Numbers

Location of Vehicle Identification Number

Shows where the vehicle identification number is stamped on the steering head.

Location of Type Label

Shows where the type label is fixed on the front of the steering head.

Location of Engine Number

Shows where the engine number is located on the engine.

Location of Fork Article Number

Shows where the fork article number is stamped on the axle clamp.

Location of Shock Absorber Article Number

Shows where the shock absorber article number is stamped.

Motorcycle Controls Overview

Clutch Lever Operation

Describes the clutch lever on the left handlebar and its hydraulic operation.

Hand Brake Lever Operation

Describes the hand brake lever on the right handlebar that engages the front brake.

Throttle Grip Operation

Describes the throttle grip on the right handlebar.

Engine Switch-off Button

Explains the function and states of the switch-off button on the left handlebar.

Engine Start Button

Describes the start button on the right handlebar and its states.

Combination Switch Functions

Details the functions of the combination switch on the left handlebar for engine mapping and controls.

Indicator Lamp Meanings

Explains the meaning of the malfunction and fuel level warning lamps.

Service Hour Counter

Explains the function of the service hour counter and its non-adjustable value.

Opening the Fuel Tank Filler Cap

Provides instructions and safety warnings for opening the fuel tank cap.

Closing the Fuel Tank Filler Cap

Provides instructions for closing the fuel tank filler cap and routing the breather hose.

Cold Start Button Function

Explains the function of the cold start button for fuel injection systems.

Idle Speed Adjustment

Describes how to adjust the idle speed using the adjusting screw.

Shift Lever Operation

Shows the shift lever and gear positions for SX-F and XC-F models.

Foot Brake Lever Operation

Describes the location and function of the foot brake lever for the rear brake.

SX-F Plug-in Stand

Explains the use of the plug-in stand for parking and transport.

XC-F Side Stand

Describes the location and use of the side stand, and its securing requirement.

Factory Start System (XC-F Kailub Russell)

Explains the activation and function of the Factory Start system on specific models.

Preparing the Motorcycle for Use

First Use Preparation Advice

Covers rider fitness, protective clothing, tire patterns, riding style, passenger, brake use, weight limits, and pre-sales inspection.

Engine Running-in Procedure

Provides guidelines for engine break-in, including speed and performance limits.

Low Temperature Battery Performance

Explains battery performance and starting issues in cold temperatures.

Preparing for Difficult Conditions

Advises on preparing the vehicle for challenging conditions like sand, mud, and extreme temperatures.

Preparing for Dry Sand Riding

Details mounting specific air filter covers for dry sand riding.

Preparing for Wet Sand Riding

Details mounting specific air filter covers for wet sand riding.

Preparing for Wet/Muddy Circuit Riding

Details mounting specific air filter covers for wet and muddy circuit riding.

Preparing for High Temperatures/Slow Riding

Advises on adjusting secondary drive and checking coolant for high temp/slow riding.

Preparing for Low Temperatures/Snow

Details mounting specific air filter covers for low temperature/snow conditions.

Riding Instructions

Pre-Ride Checks and Maintenance

Lists essential checks before every trip to ensure safe operation.

Starting the Motorcycle Engine

Provides instructions and safety warnings for starting the engine.

Activating Launch Control

Explains how launch control aids optimal acceleration at race start.

Activating Traction Control

Explains how traction control reduces rear wheel slip for better control.

Activating Factory Start (XC-F Kailub Russell)

Warns about potential freezing of the Factory Start actuator in cold weather.

Starting Off Procedure

Details the procedure for engaging gears and applying throttle to start moving.

Shifting Gears and Riding

Provides guidance on shifting, riding techniques, and engine braking.

Applying the Brakes

Offers advice on brake application, avoiding spongy points, and using engine braking.

Stopping and Parking Procedures

Covers safety warnings and procedures for stopping and parking the motorcycle.

Motorcycle Transport Guidelines

Provides instructions and safety warnings for transporting the motorcycle.

Refueling the Motorcycle

Details safety precautions and procedures for refueling.

Service Schedule

Additional Service Information

Provides details on service intervals, local conditions, and updates.

Required Service Tasks

Lists routine maintenance tasks and their intervals (e.g., after race, operating hours).

Recommended Service Tasks

Lists recommended maintenance tasks at specific intervals (e.g., every 100 operating hours, every 12 months).

Tuning the Chassis

Basic Chassis Setting with Rider Weight

Explains how to adjust suspension based on rider weight for optimal characteristics.

WP XACT 5548 Air Suspension

Describes the WP XACT 5548 air suspension system used in the fork.

Shock Absorber Compression Damping

Explains high-speed and low-speed compression damping for the shock absorber.

Adjusting Low-Speed Compression Damping

Provides step-by-step instructions for adjusting low-speed compression damping.

Adjusting High-Speed Compression Damping

Provides step-by-step instructions for adjusting high-speed compression damping.

Adjusting Rebound Damping

Provides step-by-step instructions for adjusting rebound damping of the shock absorber.

Measuring Unloaded Rear Wheel Dimension

Describes the preparatory work for measuring rear wheel dimension.

Checking Static Sag of Shock Absorber

Explains how to check static sag and lists specifications for different models.

Checking Riding Sag of Shock Absorber

Explains how to check riding sag and lists specifications for different models.

Adjusting Shock Absorber Spring Preload

Provides detailed steps for adjusting the spring preload of the shock absorber.

Adjusting Riding Sag

Details the process of adjusting the riding sag of the shock absorber.

Checking Basic Fork Setting

Notes that exact riding sag cannot be determined for the fork.

Adjusting Fork Air Pressure

Explains how to adjust fork air pressure and lists specifications.

Adjusting Fork Compression Damping

Provides instructions for adjusting fork compression damping.

Adjusting Fork Rebound Damping

Provides instructions for adjusting fork rebound damping.

Handlebar Mounting Positions

Describes the two possible mounting positions for the handlebar.

Adjusting Handlebar Position

Details how to adjust the handlebar position for rider comfort.

Chassis Service and Maintenance

Raising Motorcycle with Lift Stand

Provides instructions and safety notes for raising the motorcycle on a lift stand.

Removing Motorcycle from Lift Stand

Details how to safely remove the motorcycle from the lift stand.

Bleeding the Fork Legs

Explains the procedure for releasing pressure from the fork legs.

Cleaning Fork Leg Dust Boots

Describes how to clean dust boots to prevent oil seal leaks.

Removing Fork Protectors

Details the steps to remove the fork protectors.

Installing Fork Protectors

Details the steps to install the fork protectors with torque specifications.

Removing XC-F US Kailub Russell Motor Guard

Step-by-step instructions for removing the motor guard on specific models.

Installing XC-F US Kailub Russell Motor Guard

Step-by-step instructions for installing the motor guard on specific models.

Removing the Fork Legs

Details the process of removing the fork legs, including brake caliper and wheel spindle.

Installing the Fork Legs

Provides instructions for positioning and tightening fork legs and triple clamps.

Removing the Lower Triple Clamp

Details the removal of the lower triple clamp and associated components.

Installing the Lower Triple Clamp

Provides instructions for cleaning, greasing, and installing the lower triple clamp.

Checking Steering Head Bearing Play

Explains how to check for steering head bearing play and its importance.

Adjusting Steering Head Bearing Play

Details the procedure for adjusting steering head bearing play.

Lubricating Steering Head Bearing

Notes that lubrication occurs during the removal/installation of the lower triple clamp.

Removing the Start Number Plate

Details the steps for removing the start number plate.

Installing the Start Number Plate

Details the steps for installing the start number plate.

Removing the Front Fender

Details the steps for removing the front fender.

Installing the Front Fender

Details the steps for installing the front fender with torque specifications.

Removing the Shock Absorber

Provides detailed steps for removing the shock absorber.

Installing the Shock Absorber

Provides detailed steps for installing the shock absorber with torque specifications.

Removing the Seat

Details the steps for removing the seat, with a warning about the voltage regulator.

Mounting the Seat

Details the steps for mounting the seat with torque specifications.

Removing the Air Filter Box Cover

Details the steps for removing the air filter box cover.

Installing the Air Filter Box Cover

Details the steps for installing the air filter box cover with torque specifications.

Removing the Air Filter

Warns about operating without an air filter and its effect on engine life.

Cleaning Air Filter and Air Filter Box

Provides instructions for cleaning the air filter and box, with warnings about cleaning agents.

Installing the Air Filter

Details the steps for installing the clean air filter correctly.

Preparing Air Filter Box Cover for Securing

Describes drilling a hole in the air filter box cover for securing.

Removing the Main Silencer

Warns about the hot exhaust system and provides steps for silencer removal.

Installing the Main Silencer

Provides steps for installing the main silencer with torque specifications.

Changing Main Silencer Glass Fiber Filling

Explains how to change the glass fiber yarn filling in the main silencer.

Removing the Fuel Tank

Details safety warnings and steps for removing the fuel tank.

Installing the Fuel Tank

Details safety warnings and steps for installing the fuel tank.

Checking Chain for Dirt Accumulation

Describes how to check the chain for dirt accumulation.

Cleaning the Motorcycle Chain

Provides instructions for cleaning the chain, with safety warnings.

Checking Chain Tension

Explains how to check chain tension and lists the specification.

Adjusting Chain Tension

Details the procedure for adjusting chain tension.

Checking Chain, Sprockets, and Guide

Describes how to check for wear on the chain, sprockets, and chain guide.

Checking the Frame for Damage

Advises checking the frame for cracks or deformation due to mechanical impact.

Checking the Link Fork

Advises checking the link fork for damage, cracking, or deformation.

Checking Throttle Cable Routing

Explains the correct routing of throttle cables and how to correct it.

Checking Rubber Grips

Describes how to check rubber grips for damage, wear, and looseness.

Adjusting Clutch Lever Basic Position

Details how to adjust the clutch lever position for rider comfort.

Checking/Correcting Hydraulic Clutch Fluid Level

Explains how to check and correct the hydraulic clutch fluid level.

Changing Hydraulic Clutch Fluid

Provides step-by-step instructions for changing the hydraulic clutch fluid.

Brake System Maintenance and Operation

Checking Hand Brake Lever Free Travel

Explains how to check free travel and what to do if it doesn't match the specification.

Adjusting Hand Brake Lever Position

Details how to adjust the hand brake lever position for rider comfort.

Checking Brake Discs for Wear

Warns about worn brake discs reducing braking effect and requiring immediate replacement.

Checking Front Brake Fluid Level

Explains how to check the front brake fluid level and what to do if it's low.

Adding Front Brake Fluid

Provides instructions and safety warnings for adding front brake fluid.

Checking Front Brake Linings

Explains how to check front brake lining thickness and for damage.

Changing Front Brake Linings

Warns about incorrect servicing and provides steps for changing front brake linings.

Checking Foot Brake Lever Free Travel

Explains how to check foot brake lever free travel and adjust if needed.

Adjusting Foot Brake Lever Position

Details how to adjust the foot brake lever position for individual requirements.

Checking Rear Brake Fluid Level

Explains how to check the rear brake fluid level and what to do if it's low.

Adding Rear Brake Fluid

Provides instructions and safety warnings for adding rear brake fluid.

Checking Rear Brake Linings

Explains how to check rear brake lining thickness and for damage.

Changing Rear Brake Linings

Warns about incorrect servicing and provides steps for changing rear brake linings.

Wheels and Tires

Removing the Front Wheel

Details steps for removing the front wheel, including brake caliper and spindle.

Installing the Front Wheel

Provides instructions for installing the front wheel, checking bearings and greasing.

Removing the Rear Wheel

Details steps for removing the rear wheel, including chain adjuster and spindle.

Installing the Rear Wheel

Provides instructions for installing the rear wheel, checking bearings and greasing.

Checking Tire Condition

Advises on checking tires for cuts, damage, and wear for safe handling.

Checking Tire Pressure

Explains how to check tire pressure when cold and lists specifications.

Checking Spoke Tension

Warns about improperly tensioned spokes and how to check them.

Electrical System

Removing the 12-V Battery

Details steps for safely removing the 12-V battery.

Installing the 12-V Battery

Provides instructions for installing the 12-V battery and connecting cables.

Charging the 12-V Battery

Explains how to charge the 12-V battery, with warnings and tips for battery life.

Changing the Main Fuse

Details how to change the main fuse, with warnings about electrical overload.

Diagnostics Connector Location

Indicates the location of the diagnostics connector under the seat.

Cooling System

Cooling System Overview

Explains the function of the water pump and radiator cap in the cooling system.

Checking Antifreeze and Coolant Level

Provides instructions and safety warnings for checking antifreeze and coolant levels.

Checking Coolant Level

Details how to check the coolant level in the radiator and safety precautions.

Draining the Coolant

Provides safety warnings for draining the coolant.

Refilling Coolant

Details how to refill coolant and check the level after a test ride.

Changing the Coolant

Provides safety warnings and steps for changing the coolant.

Tuning the Engine

Checking Throttle Cable Play

Explains how to check throttle cable play and related conditions.

Adjusting Throttle Cable Play

Details how to adjust the throttle cable play for optimal response.

Adjusting Throttle Response Map

Explains how to change the throttle response map using guide plates.

Changing Engine Mapping

Explains how to activate different engine mapping modes (STANDARD, ADVANCED).

Adjusting Idle Speed

Warns about setting idle speed too low and the need for proper adjustment.

Programming Throttle Valve Position

Explains how to reprogram the throttle valve position if needed.

Checking Basic Shift Lever Position

Explains how to check the shift lever position relative to the rider's boot.

Adjusting Basic Shift Lever Position

Details how to adjust the shift lever position for rider comfort and function.

Engine Service and Maintenance

Changing the Fuel Screen

Details safety warnings and steps for changing the fuel screen.

Checking Engine Oil Level

Explains how to check the engine oil level when cold or warm.

Changing Engine Oil and Filter, Cleaning Oil Screen

Provides detailed steps for changing engine oil, oil filter, and cleaning the oil screen.

Adding Engine Oil

Explains how to add engine oil and warns against mixing oil types.

Cleaning and Care

Cleaning the Motorcycle

Provides instructions and warnings for cleaning the motorcycle, avoiding high pressure.

Motorcycle Storage

Motorcycle Storage Procedures

Outlines steps for preparing the motorcycle for longer-term storage.

Preparing for Use After Storage

Details the steps to take when bringing the motorcycle out of storage.

Troubleshooting Guide

Common Faults and Solutions

Lists common motorcycle faults, their possible causes, and recommended actions.

Blink Code Diagnostics

Malfunction Indicator Lamp Blink Codes

Lists blink codes and their corresponding error level conditions for diagnostics.

Technical Data

Engine Specifications

Provides detailed technical specifications for the engine.

Engine Tightening Torques

Lists torque specifications for various engine components.

Fluid Capacities

Lists capacities for engine oil, coolant, and fuel.

Chassis Specifications

Provides technical specifications for the chassis components.

Electrical System Specifications

Lists specifications for the battery, fuse, and indicator lamps.

Tire Specifications

Lists recommended tire sizes and validity for SX-F and XC-F models.

Fork Specifications

Provides specifications for fork settings like compression and rebound damping.

Shock Absorber Specifications

Lists specifications for shock absorber settings, spring preload, and sag.

Chassis Tightening Torques

Lists torque specifications for various chassis components.

Substances and Fluids

Brake Fluid Specifications

Details brake fluid standards, recommended suppliers, and usage guidelines.

Coolant Specifications

Provides coolant guidelines, antifreeze protection, and recommended suppliers.

Engine Oil Specifications

Details engine oil standards, recommended suppliers, and usage guidelines.

Auxiliary Substances and Lubricants

Air Filter Cleaner

Lists recommended air filter cleaner products.

Chain Cleaner

Lists recommended chain cleaner products.

Fuel Additive

Lists recommended fuel additive products.

High Viscosity Grease

Lists recommended high viscosity grease products.

Long-Life Grease

Lists recommended long-life grease products.

Motorcycle Cleaner

Lists recommended motorcycle cleaner products.

Off-Road Chain Spray

Lists recommended off-road chain spray products.

Oil for Foam Air Filter

Lists recommended oil for foam air filters.

Preserving Materials for Paints, Metal, Rubber

Lists recommended products for preserving surfaces.

Standards and Classifications

JASO T903 MA2 Standard

Explains the JASO T903 MA2 standard for motorcycle oils.

SAE Viscosity Classification

Explains the SAE viscosity classification system for oils.

Index of Special Terms

Launch Control Definition

Defines launch control as an electronic function for optimal acceleration.

OBD Definition

Defines OBD as a vehicle system monitoring electronic parameters.

List of Abbreviations

Abbreviation for Article Number

Defines the abbreviation "Art. no." as Article number.

Abbreviation for Circa

Defines the abbreviation "ca." as circa.

Abbreviation for Compare

Defines the abbreviation "cf." as compare.

Abbreviation for Example

Defines the abbreviation "e.g." as for example.

Abbreviation for Et Cetera

Defines the abbreviation "etc." as et cetera.

Abbreviation for Inter Alia

Defines the abbreviation "i.a." as inter alia.

Abbreviation for Number

Defines the abbreviation "no." as number.

Abbreviation for Possibly

Defines the abbreviation "poss." as possibly.

List of Symbols

Yellow and Orange Symbol Meanings

Explains the meaning of yellow and orange symbols indicating errors or active driving aids.

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