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KTM 250 SX-F 2017
SMALL-BORE SUPERSTAR

 
  The new KTM 250 SX with its all-new engine has one of the best power-to-weight ratios in the world of dirt, forming the ultimate fist against more complex 4-stroke rivals. With the grunt to devour all sorts of tracks and terrains, and a lightweight chassis keen to skim the surface, this lovechild of KTM’s R&D and Motorsport departments is born to lead the next pack of winners into a hazy blue future.  
     
   
     
 

FIREBALL

 
                         
                   
   

ENGINE

     

CYLINDER

     

ENGINE CASES

   
    The engine of the 250 SX has been known and respected for being the most powerful 2-stroke engine in its class. But we thought the segment could use an extra push and a solid statement: 2-strokes have a future at KTM. Their outstanding power-to-weight ratio, low cost and simplicity see to that. Putting our money where our mouth is, we gave the 250 SX engine an all new architecture with a new shaft arrangement for better mass centralization, a new cylinder with twin-valve controlled power valve, a new counter balance shaft for less engine vibrations, a 5-speed transmission and a hydraulically operated DDS clutch. This compact firecracker truly outshines the competition with its ripping performance and is the right choice for lovers of low purchasing and maintenance costs. Oh, and of course don’t forget that belly tingling 2-stroke symphony when you’re on the pipe.       The newly developed cylinder of the 250 SX - with a bore of 66.4mm - has all-new ports and is fitted with an overhauled power valve system. This system features a sophisticated mechanism for the lateral support exhaust ports, providing smooth and controllable power on tap. Furthermore, it’s possible to change the bike’s mood in seconds thanks to two supplied powervalve springs. Limitless settings for different tracks and preferences are up for grabs. Throw everything you have at it; new water jackets in the cylinder and head will take care of excess heat and reworked lateral cylinder head brackets allow a more efficient fixation of the engine to the frame via lightweight  head stays. Yes, this is a serious piece of kit.       These all-new die-cast engine cases feature a 8mm higher clutch shaft and a 27mm higher crankshaft, resulting in better mass centralization. Which is nice if you care about sweet rideability. In addition, it allows the implementation of a counter balance shaft. So your ride will be as relaxed as it is rapid. Plus, your new favorite engine will keep looking as fresh as the day you bought it: redesigned engine covers feature a smart surface structure in order to reduce the wear caused by the rider’s boots.    
                         
                         
                         
                   
   

COUNTER BALANCE SHAFT

     

TRANSMISSION

     

CARBURETOR

   
    Say goodbye to numb feet and hands. The new engine design allows the implementation of a lateral counter balance shaft in order to reduce the vibration level drastically (50% lower level on handlebar and foot pegs). You know what that means: more comfort, more smiles.       This reworked 5-speed gearbox has the same gear ratios as its predecessor, but our engineers took a close look at the mechanism in order to provide you with more precise and easier shifting. Keeping safety in mind, an advanced ´No Dirt´gear lever design prevents muck from blocking the joint. Because even dirt lovers hate mud when it’s in the wrong places.       As of model year 2017, all KTM 2-stroke models are fitted with new MIKUNI TMX carburetors, replacing the Keihin products. This 38mm flat slide carb lives to provide smooth and controllable power all the way up to the limiter. And it’s less sensitive to different altitudes and temperatures, so you can pin it wherever, whenever.    
                         
                         
                         
         

CRANKSHAFT

Its 72mm stroke stayed, the rest is brand new. Rebalanced, revamped and set-up with a counter balance shaft to kill vibrations, not your vibe.
     

CLUTCH

The 250 SX employs the KTM-developed DDS clutch (damped diaphragm steel) with a wear-free steel basket and extremely heat resistant clutch plates. This clever design employs a diaphragm spring instead of the usual coil springs, which makes for a considerably easier clutch action. A diaphragm spring also leaves sufficient space for a damping system to be integrated into the clutch hub. The goal was traction, yes, but durability as well. On top of that, it is fitted with a lighter basket, a reworked inner hub and a pressure plate providing better oil supply and unsurpassed cooling. Of course, light operation and telepathic amounts of control are what make this particular clutch, a hydraulic Brembo clutch.
   
   

EXHAUST

               
    The engineers meticulously tuned the expansion chamber for maximum power. An advanced 3-D production process now guarantees higher precision manufacturing, so this little screamer is as tough as it is strong.                
                         
                         
 

SLIM AND SMART

 
                         
                   
   

FRAME

     

HANDLEBAR

     

COOLING SYSTEM

   
    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, lightweight  engine head stays (the connection between cylinder head and frame) contribute to  precise cornering and a reduced vibration level. The engineers were able to pull off all that, while making their frame a big fat kilogram 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 stable aluminum profiles, which tiptoes the scales at less than 900g.       KTM engineers sure know how to handle handlebars. This tapered one, made of high-strength aluminum by NEKEN, is fixed in damped rubber mountings and has two different positions. From MY2017 onwards, the lower handlebar clamps are separated, while on the upper side a new bridge-type clamp guarantees more torsional stiffness. It’s also easier to replace the bar in case it gets twisted in a nasty crash. An ODI volcanized grip sits on the right, while on the left side of the bar a comfortable ODI lock-on grip is mounted, which does not require any wire or glue to be fixed.       KTM’s proven cooling system routes the coolant from the cylinder head through the frame triangle, directly to aluminum radiators made by WP. 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 spoilers provide protection in case of crashes. Which is also pretty cool.    
                         
                         
                         
                   
   

AIRBOX

     

SWINGARM

     

SEAT

   
    The airbox design offers maximum protection of the air filter against soiling, 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.       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 too.       Tailored to meet the needs of the world’s fastest backsides, this durable seat offers great comfort. For MY2017, a new cover pampers its riders even more with better feel and grip.    
                         
                         
                         
                   
   

FUEL TANK

     

FOOTPEGS

     

WHEELS

   
    A lightweight polyethylene tank with a capacity of 7.0 liters of juice. The filler cap has an inside thread, which makes for easy and reliable closure.         Sophisticated ´No Dirt´ footpegs prevent smudging up the pegs, 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.       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.    
                         
                         
     
 

FEATHERWEIGHT

 
  KTM engineers just love dropping weight year after year. The result: the 2017 SX models are the slimmest, lightest dirt bikes out there.  
     
     
 

WORLD-PROOF

 
                         
                   
   

MONOSHOCK

     

FORKS

     

TRIPLE CLAMP

   
    The WP monoshock has been developed with the entire frame and swingarm architecture in mind, including the linkage system and the WP AER 48 front forks. It features machined and black anodized components and is a valuable, high-end product compared to roughcast reservoirs. A new setting and a softer spring perfectly match the reworked front-end set-up and its sparkling WP color scheme lets everyone know you have excellent taste in suspension.       The lightweight WP AER 48 front fork, a 48mm 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 two-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 air pump supplied with the bike will do just fine. 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). For MY2017, the AER 48 also features redesigned outer tubes with better bending characteristics, smoother operation and less friction. Plus: they’ve lost some weight (265g). Right off the dealer floor, these forks are more comfortable and more sensitive than ever. But you can still hammer the hell out of them.       Top quality, CNC machined triple clamps have been something of a KTM trademark for years. Ensuring a precise handling, they perceptibly support the flex characteristics, and with it the action of the forks. For MY2017, the upper triple clamp specifically features a redesign in conjunction with the new fork tubes. The rubber damped handlebar fixation 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. Or a cold drink.    
                         
                         
                         
                       
   

BRAKES

     

 

           
    You couldn’t brake any harder, better, faster or stronger. These high-tech Brembo babies are combined with lightweight wave discs made by Galfer. For MY2017, the rear brake features a 10mm longer brake pedal and you get new, less aggressive brake pads all round.                    
                         
                         
 

STRIKING GOOD LOOKS

 
                         
                     
   

BODYWORK

     

GRAPHICS

     

 

   
    KTM R&D, Kiska Design and all our factory riders had their say in shaping the plastics. Their goal: complete harmony between rider and bike. And so it turned out. Perfect ergonomics and contact points, maximum freedom of movement, a low seat height and sweet comfort, especially in the rear part of the seat. The I-beam structures of the front and rear fenders are prime examples of such an intelligent design, guaranteeing maximum stability and a low weight thanks to well thought-out construction and mounting. Plus: they stay cleaner for longer.       A new, tailor-made kit, fit for a king. Because in this sport, champs deserve to look the part regardless of the dirt.            
                         
                         
 
 
     
 

ENGINE

 
 
  • Design

  • 1-cylinder, 2-stroke engine


    • Displacement

      249 cm³


    • Bore

      66.4 mm




 
  • Stroke

    72 mm


  • Starter

    Kickstarter


  • Transmission

    5-speed





 
  • Primary drive

    26:73


  • Secondary gear ratio

    14:50


  • Clutch

    Wet, DDS multi-disc clutch, Brembo hydraulics


  • EMS

    Kokusan





 
             
 

SHASSIS

 
 
  • Frame design

    Chrome-molybdenum steel central-tube frame


  • Front suspension

    WP-USD, AER 48, Ø 48 mm


  • Rear suspension

    WP shock absorber with linkage


  • Suspension travel (front)

    310 mm


  • Suspension travel (rear)

    300 mm




 
  • Front brake

    Disc brake


  • Rear brake

    Disc brake


  • Front brake disc diameter

    260 mm


  • Rear brake disc diameter

    220 mm


  • Chain

    5/8 x 1/4"


 
  • Steering head angle

    63.9 °


  • Wheelbase

    1485 ± 10 mm


  • Ground clearance

    375 mm


  • Seat height

    960 mm


  • Tank capacity (approx.)

    7 l


  • Weight READY TO RACE (without fuel)

    95.4 kg


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