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2018 KTM 125 SX
2018 KTM 125 SX

Specs

General Information

Manufacturer
KTM
KTM
Model Year
2018
2018
Model
125 SX
125 SX
Model Code
125SX
125SX
Color
Orange / White
Orange / White

Brakes/Wheels/Tires

Brakes

Front - 260 mm Disc

Rear - 220 mm Disc

Front - 260 mm Disc

Rear - 220 mm Disc

Wheels

Front - 1.6 x 21

Rear - 2.15 x 19 Excel

Front - 1.6 x 21

Rear - 2.15 x 19 Excel

Tires

Front - 80 / 100-21 in.

Rear - 100 / 90-19 in. Dunlop MX3S

Front - 80 / 100-21 in.

Rear - 100 / 90-19 in. Dunlop MX3S

Dimensions

Weight
Without Fuel - 192.24 lb. (87.2 kg)
Without Fuel - 192.24 lb. (87.2 kg)
Ground Clearance
14.8 in. (375 mm)
14.8 in. (375 mm)
Wheelbase
58.5 ± 0.4 in. (1,485 mm ± 10 mm)
58.5 ± 0.4 in. (1,485 mm ± 10 mm)
Seat Height
37.8 in. (960 mm)
37.8 in. (960 mm)

Drivetrain

Transmission
6-speed
6-speed
Primary Drive
23:73
23:73
Final Drive

13:50

Chain - 5/8 x 1/4 in.

13:50

Chain - 5/8 x 1/4 in.

Engine

Engine
1-cylinder, 2-stroke
1-cylinder, 2-stroke
Cooling
Liquid
Liquid
Displacement
124.8 cc
124.8 cc
Bore x Stroke
54 x 54.5 mm
54 x 54.5 mm
Gear Ratio
Secondary - 13:50
Secondary - 13:50
Clutch
Wet, multi-disc; Brembo hydraulics
Wet, multi-disc; Brembo hydraulics
Fuel System
Kokusan
Kokusan
Starting
Kick
Kick
Lubrication
Premix 40:1
Premix 40:1
Fuel Capacity
1.85 gal.
1.85 gal.

Operational

Frame

25CrMo4 Steel central-Tube

Handlebar - Neken, Aluminum, Ø 28/22 mm

25CrMo4 Steel central-Tube

Handlebar - Neken, Aluminum, Ø 28/22 mm

Suspension

Front - WP-USD, AER 48, Ø 48 mm; Travel - 12.2 in.

Rear - WP shock absorber with linkage; Travel - 11.81 in.

Front - WP-USD, AER 48, Ø 48 mm; Travel - 12.2 in.

Rear - WP shock absorber with linkage; Travel - 11.81 in.

Rake
63.9°
63.9°

Features

Looks That Matter

  • BODYWORK: KTM R&D, Kiska Design and the factory racers had their say in shaping the plastics with one goal: complete harmony between rider and bike. Perfect ergonomics and contact points provide maximum comfort in movement on the SX-F. The I-beam structures of the front and rear fenders guarantee maximum stability and a low weight thanks to well thought-out construction and mounting. They also stay cleaner for longer.
  • GRAPHICS: New graphics convey the READY TO RACE character of the 2018 SX model line.

Sleek and Slick

  • WEIGHT: The main target for the KTM engineers when developing the SX models was a massive weight reduction compared to the previous generation. The result: the current SX models are the slimmest, lightest bikes on the track.
  • FRAME: The high-tech, lightweight chrome-moly steel frame has a knack for easy handling, outlandish rideability, precise cornering and excellent stability. You can also count on high torsional rigidity and low longitudinal stiffness. This results in better absorption of the energy created from the front and rear suspension, sucking up jumps and bumps. In short: more comfort and less rider fatigue. Laterally attached, engine head stays (the connection between cylinder head and frame) are now made of lightweight aluminum. They contribute to more precise cornering and a reduced vibration level. The engineers were able to pull off all that, while making their frame 2.2 pounds lighter than that of the lightest competitor on the market. In addition, it is easier to maintain, easier to work on and supplies more space for the tank and other components. The bike also features an extra-light subframe made of aluminum, which tips the scales at less than 2 pounds.
  • FOOTPEGS: Sophisticated ´No Dirt´ footpegs prevent clogging of the footpeg pivot, even when digging in deep ruts. Looking for a higher riding position? Then just mount the footpegs of the MY2017 EXC models, which are 6mm higher than the SX versions.
  • AIR FILTER BOX: The airbox design offers maximum protection of the air filter while ensuring maximum airflow. The large twin-air filter is mounted in a stiff cage, which at the same time holds the system in place. This design is so simple you could still pop a fresh one in with a face full of mud. Without tools. In seconds.
  • HANDLEBAR: KTM engineers sure know how to handle handlebars. This tapered unit, made of high-strength aluminum, is fixed in damped rubber mounts and has two different positions. ODI lock-on grips make grip changes easy and do not require any wire or glue to be secured.
  • SWINGARM: The cast aluminum design offers low weight and a perfect flex behavior. The single-component casting process eliminates any inconsistencies and inherent weak points created by welding. It’s better looking as well.
  • FUEL TANK: A lightweight polyethylene tank with a capacity of 1.85 gallons. The fuel tank cap has an inside thread, which makes for easy and reliable closure.
  • WHEELS: Featuring lightweight, CNC machined hubs and high-end Excel rims, they guarantee maximum stability and minimal unsprung weight. The wheels are shod with the latest Dunlop Geomax MX 3S tires.
  • COOLING SYSTEM: KTM’s proven cooling system routes the coolant from the cylinder head through the frame triangle, directly to aluminum radiators made by WP. A filler cap system and stiffer alloy construction increase the durability and reliability of the cooling system. Due to flow optimized internal circulation and CFD-calculated air ventilation, the system is superbly efficient. In addition, well thought-out radiator guards integrated in the front part of the shrouds provide protection in a crash.

Small Bore, Big Power

  • ENGINE: The latest KTM 125 SX engine is the most powerful and most competitive engine in its class; a clear statement that KTM is keen on keeping 2-stroke technology at the forefront of development. The secret to their success is an outstanding power-to-weight ratio, low costs and simplicity. This 125 cc ripper has been developed with the latest KTM engineering know-how and the most advanced technology available. The results: class-leading power across the rev range, while being extremely compact and ultra-light at a mere 39.5 pounds. Our work here is done; now it’s up to you to collect the trophies.
  • CYLINDER: This compact cylinder with a 54mm bore features a cutting-edge power valve unit with a sophisticated mechanism for the lateral support exhaust ports. Matched to a twin-component cylinder head, it is KTM’s secret to all-round grunt. The layout of the water jackets in the cylinder and head guarantees efficient heat dissipation when the going gets tough.
  • CRANKCASES: For the latest engine generation the KTM engineers designed lightweight die-cast engine cases featuring a high crankshaft position located close to the center of gravity, which results in optimal mass centralization and outstanding rideability.
  • CRANKSHAFT: This reliable piece of engineering has been skillfully balanced to guarantee minimal vibrations. In its latest form, it allows an increase of the displacement to 144 cc just by replacing cylinder, piston and head. There’s no longer the need to change the crankshaft if you want to change displacement. Two-in-one in no time.
  • TRANSMISSION: A robust 6-speed transmission was designed specifically for the small 2-stroke engine, its gear ratios are perfectly in sync with the 125’s power band. The latest production technologies allow for compact dimensions and minimal weight. An advanced ´No Dirt´ gear lever design prevents mud from clogging the folding tip for reliable shifts even in the worst conditions.
  • CARBURETOR: The KTM 125 SX is fitted with a MIKUNI TMX carburetor. This 38mm flat slide carb lives to provide smooth and controllable power all the way up to the rev limitation. With a new intake manifold the carburetor is turned 7° in order to reduce the overflow of fuel. And it’s less sensitive to different altitudes and temperatures, so you can pin it wherever, whenever.
  • EXHAUST: The engineers meticulously tuned the expansion chamber for maximum torque and power, so this screamer is as tough as it is strong.
  • IGNITION: All 2-stroke models feature a new CDI control unit with an advanced hardware which improves the starting behavior of the engine. The ignition curves remain unchanged.

You Can Handle It

  • SHOCK ABSORBER: The WP shock absorber has been developed with the entire frame and swingarm architecture in mind, including the linkage and the WP AER 48 front fork. It features machined and black anodized components and is a valuable, high-end product compared to roughcast reservoirs. A new, confidence inspiring setting with improved damping characteristics perfectly matches the front-end setup and its WP color scheme lets everyone know you have excellent taste in suspension.
  • FORK: The lightweight WP AER 48 front fork, a 48 mm USD air-sprung fork developed by WP in close collaboration with KTM, is a split fork with separate functions for each leg. That means damping functions are on the right side, whereas the air spring is in the left. This left leg features a 2-chamber system with a capsuled air cartridge to prevent loss of air pressure. Should the outer seal start to leak, the internal cartridge pressure will keep the bike in position. The air spring is easy to adjust to any rider weight via a single air valve. No special tools are required; the fork air pump is supplied with the bike. The right fork leg integrates a damping cartridge that tailors to all your damping needs. It can be adjusted to the track conditions and the rider’s preferences with a twist of a dial (compression from the top, rebound from the bottom, 30 clicks each). Right off the dealer floor, this fork (with reworked damping characteristics) is more comfortable and more sensitive than ever.
  • TRIPLE CLAMP: Top quality, CNC machined triple clamps have been a KTM trademark for years to ensure precise handling. For 2017, the upper triple clamp specifically features a redesign in conjunction with the new fork tubes. The rubber damped handlebar mount has also been reworked and the lower handlebar clamps are now separated, while on the upper side a new bridge-type clamp guarantees more torsional stiffness and can easily be replaced in case it gets twisted due to a crash. In addition, an hour meter is fitted at the upper triple clamp in order to let the rider know it’s time for a service.
  • BRAKES: You can’t brake any harder, better, faster or stronger. These high-tech Brembo babies are combined with lightweight wave discs made by Galfer. For 2017, the rear brake features a 10 mm longer brake pedal and you get new, less aggressive brake pads all round.

Looks That Matter

  • BODYWORK: KTM R&D, Kiska Design and the factory racers had their say in shaping the plastics with one goal: complete harmony between rider and bike. Perfect ergonomics and contact points provide maximum comfort in movement on the SX-F. The I-beam structures of the front and rear fenders guarantee maximum stability and a low weight thanks to well thought-out construction and mounting. They also stay cleaner for longer.
  • GRAPHICS: New graphics convey the READY TO RACE character of the 2018 SX model line.

Sleek and Slick

  • WEIGHT: The main target for the KTM engineers when developing the SX models was a massive weight reduction compared to the previous generation. The result: the current SX models are the slimmest, lightest bikes on the track.
  • FRAME: The high-tech, lightweight chrome-moly steel frame has a knack for easy handling, outlandish rideability, precise cornering and excellent stability. You can also count on high torsional rigidity and low longitudinal stiffness. This results in better absorption of the energy created from the front and rear suspension, sucking up jumps and bumps. In short: more comfort and less rider fatigue. Laterally attached, engine head stays (the connection between cylinder head and frame) are now made of lightweight aluminum. They contribute to more precise cornering and a reduced vibration level. The engineers were able to pull off all that, while making their frame 2.2 pounds lighter than that of the lightest competitor on the market. In addition, it is easier to maintain, easier to work on and supplies more space for the tank and other components. The bike also features an extra-light subframe made of aluminum, which tips the scales at less than 2 pounds.
  • FOOTPEGS: Sophisticated ´No Dirt´ footpegs prevent clogging of the footpeg pivot, even when digging in deep ruts. Looking for a higher riding position? Then just mount the footpegs of the MY2017 EXC models, which are 6mm higher than the SX versions.
  • AIR FILTER BOX: The airbox design offers maximum protection of the air filter while ensuring maximum airflow. The large twin-air filter is mounted in a stiff cage, which at the same time holds the system in place. This design is so simple you could still pop a fresh one in with a face full of mud. Without tools. In seconds.
  • HANDLEBAR: KTM engineers sure know how to handle handlebars. This tapered unit, made of high-strength aluminum, is fixed in damped rubber mounts and has two different positions. ODI lock-on grips make grip changes easy and do not require any wire or glue to be secured.
  • SWINGARM: The cast aluminum design offers low weight and a perfect flex behavior. The single-component casting process eliminates any inconsistencies and inherent weak points created by welding. It’s better looking as well.
  • FUEL TANK: A lightweight polyethylene tank with a capacity of 1.85 gallons. The fuel tank cap has an inside thread, which makes for easy and reliable closure.
  • WHEELS: Featuring lightweight, CNC machined hubs and high-end Excel rims, they guarantee maximum stability and minimal unsprung weight. The wheels are shod with the latest Dunlop Geomax MX 3S tires.
  • COOLING SYSTEM: KTM’s proven cooling system routes the coolant from the cylinder head through the frame triangle, directly to aluminum radiators made by WP. A filler cap system and stiffer alloy construction increase the durability and reliability of the cooling system. Due to flow optimized internal circulation and CFD-calculated air ventilation, the system is superbly efficient. In addition, well thought-out radiator guards integrated in the front part of the shrouds provide protection in a crash.

Small Bore, Big Power

  • ENGINE: The latest KTM 125 SX engine is the most powerful and most competitive engine in its class; a clear statement that KTM is keen on keeping 2-stroke technology at the forefront of development. The secret to their success is an outstanding power-to-weight ratio, low costs and simplicity. This 125 cc ripper has been developed with the latest KTM engineering know-how and the most advanced technology available. The results: class-leading power across the rev range, while being extremely compact and ultra-light at a mere 39.5 pounds. Our work here is done; now it’s up to you to collect the trophies.
  • CYLINDER: This compact cylinder with a 54mm bore features a cutting-edge power valve unit with a sophisticated mechanism for the lateral support exhaust ports. Matched to a twin-component cylinder head, it is KTM’s secret to all-round grunt. The layout of the water jackets in the cylinder and head guarantees efficient heat dissipation when the going gets tough.
  • CRANKCASES: For the latest engine generation the KTM engineers designed lightweight die-cast engine cases featuring a high crankshaft position located close to the center of gravity, which results in optimal mass centralization and outstanding rideability.
  • CRANKSHAFT: This reliable piece of engineering has been skillfully balanced to guarantee minimal vibrations. In its latest form, it allows an increase of the displacement to 144 cc just by replacing cylinder, piston and head. There’s no longer the need to change the crankshaft if you want to change displacement. Two-in-one in no time.
  • TRANSMISSION: A robust 6-speed transmission was designed specifically for the small 2-stroke engine, its gear ratios are perfectly in sync with the 125’s power band. The latest production technologies allow for compact dimensions and minimal weight. An advanced ´No Dirt´ gear lever design prevents mud from clogging the folding tip for reliable shifts even in the worst conditions.
  • CARBURETOR: The KTM 125 SX is fitted with a MIKUNI TMX carburetor. This 38mm flat slide carb lives to provide smooth and controllable power all the way up to the rev limitation. With a new intake manifold the carburetor is turned 7° in order to reduce the overflow of fuel. And it’s less sensitive to different altitudes and temperatures, so you can pin it wherever, whenever.
  • EXHAUST: The engineers meticulously tuned the expansion chamber for maximum torque and power, so this screamer is as tough as it is strong.
  • IGNITION: All 2-stroke models feature a new CDI control unit with an advanced hardware which improves the starting behavior of the engine. The ignition curves remain unchanged.

You Can Handle It

  • SHOCK ABSORBER: The WP shock absorber has been developed with the entire frame and swingarm architecture in mind, including the linkage and the WP AER 48 front fork. It features machined and black anodized components and is a valuable, high-end product compared to roughcast reservoirs. A new, confidence inspiring setting with improved damping characteristics perfectly matches the front-end setup and its WP color scheme lets everyone know you have excellent taste in suspension.
  • FORK: The lightweight WP AER 48 front fork, a 48 mm USD air-sprung fork developed by WP in close collaboration with KTM, is a split fork with separate functions for each leg. That means damping functions are on the right side, whereas the air spring is in the left. This left leg features a 2-chamber system with a capsuled air cartridge to prevent loss of air pressure. Should the outer seal start to leak, the internal cartridge pressure will keep the bike in position. The air spring is easy to adjust to any rider weight via a single air valve. No special tools are required; the fork air pump is supplied with the bike. The right fork leg integrates a damping cartridge that tailors to all your damping needs. It can be adjusted to the track conditions and the rider’s preferences with a twist of a dial (compression from the top, rebound from the bottom, 30 clicks each). Right off the dealer floor, this fork (with reworked damping characteristics) is more comfortable and more sensitive than ever.
  • TRIPLE CLAMP: Top quality, CNC machined triple clamps have been a KTM trademark for years to ensure precise handling. For 2017, the upper triple clamp specifically features a redesign in conjunction with the new fork tubes. The rubber damped handlebar mount has also been reworked and the lower handlebar clamps are now separated, while on the upper side a new bridge-type clamp guarantees more torsional stiffness and can easily be replaced in case it gets twisted due to a crash. In addition, an hour meter is fitted at the upper triple clamp in order to let the rider know it’s time for a service.
  • BRAKES: You can’t brake any harder, better, faster or stronger. These high-tech Brembo babies are combined with lightweight wave discs made by Galfer. For 2017, the rear brake features a 10 mm longer brake pedal and you get new, less aggressive brake pads all round.