4 years ago

Dirt and Trail July 2018 issue 2

  • Text
  • Durability
  • Bikes
  • Riders
  • Suspension
  • Enduro
  • Motorcycles
  • Models
  • Racing
  • Clutch
  • Trophy

The upper triple clamp

The upper triple clamp has been revised and is stiffer to coincide with the new frame and flex characteristics of the latest WP AER 48 fork. The swingarm now has a longer rear axle slot that allows the rear wheel to be adjusted up to 5mm farther back than prior year models and the subframes are 40mm longer to improve rear fender stability. The radiators have been redesigned and are mounted 12mm lower, and a redesigned coolant tube integrated in the frame triangle features a 4mm-larger center tube increasing the cross section by 57 percent. The fuel tanks have also been changed to improve the ergonomics. The final touches to the bikes are updated spoke nipples (designed to be more maintenance-free), new bodywork, a new seat shape, a revised bar pad and cover, and new graphics. Lastly, all KTM motocross bikes now come with a new triangle stand that also serves as a spacer for the front wheel for tying the bike down when hauling it in a vehicle. This reduces high static pressure on the air cartridge and prevents the fork from being compressed during transport. The 125 SX and 150 SX feature a host of changes shared between the two smallbore two-strokes. Both bikes feature a new cylinder with an updated layout of the exhaust port, a newly developed diaphragm steel (DS) clutch, and a new clutch cover that is lower and reduces the width of the engine by 10mm plus a new Pankl gearbox. Pankl make gearboxes and clutches for F1 cars. We didn’t know that. The 125 SX and 150 SX have reworked carburettor settings and a new header pipe and silencer. The silencers plastic mounting system is replaced by a welded aluminum bracket and the kickstarters intermediate gear has been reinforced for better reliability. KTM’s 2019 two-strokes share the same suspension updates. The WP shock gets an updated main piston and revised settings to match with the new fork setup and provide better damping characteristics. Both the 125 SX and 150 SX have a redesigned airbox and intake snorkels, a new header pipe and silencer, and a reworked carburetor setting to work better with the new airbox and exhaust system. 250: KTM made a change specifically to the 250 SX frame for 2019 that raises the engine in the frame by one degree around the swingarm pivot to improve the handling characteristics, specifically front wheel grip. Another update is that the engine hangers (the connection between cylinder/head and frame) on the 250 SX are now made of aluminum instead of steel to improve precise cornering ability and reduce vibration. The engine boasts a revised exhaust port for more precise function of the power valve to improve power delivery and a reworked water pump casing to optimize the flow of coolant. To allow for better airflow, KTM redesigned the airbox and intake snorkels and developed a new carburetor setting to work better with the two redesigned parts. The 250 SX also has a more compact header pipe and silencer with new perforated inner tubes and lighter silencer packing to reduce noise. The new silencer equates to a weight reduction of approximately 300 grams from last year’s part. Lastly, the plastic bracket that secured the previous model’s silencer is replaced by lightweight, welded mounting brackets on the 2019 machine. Very techy stuff but some really cool updates for the new model year. The four strokes: Hydraulic clutch, electric starting, super shifting and light weight, new seats, new plastics… All 2019 KTM SXF models feature new high-tech and lightweight black chromoly steel frames in various profiles including hydro-formed elements produced by WP Performance Systems with state-of-the-art robots (Not traffic lights, actual robots). Ok, OK! They feature optimized stiffness (2% stiffer longitudinally and 10% stiffer torsionally). The head stays are aluminum for all models. New frame guards improve grip and the right one is a heat protector for the silencer. On the 250SXF, 350SXF and 450SXF there are brackets to mount a composite skid plate. The subframe is 900 grams lighter and 40mm longer than this years model. 18 DIRT & TRAIL MAGAZINE JULY 2018

The air boxes have been completely reworked for increased flow. This improves throttle response. The 250SXF, 350SXF and 450SXF get new intake snorkels for improved engine performance. The large Twin-Air air filter is mounted on a stiff cage, which minimizes incorrect installation of the filter and cage. The filter can be changed without tools in seconds, a standard, original feature by KTM. The 250SXF, 350SXF and 450SXF models are fitted with newly designed polyethylene tanks that improve ergonomics. Fuel capacity 7 litres of fuel. Exhausts The new exhausts are slimmer and well within the sound limits for racing. The 250SXF, 350SXF and 450SXF four-strokes are fitted with new, model-specific head pipes with an advanced Flow Design Header (FDH). The resonator, which was only offered on the 450 last year, is better integrated into the pipe, making the front part of the exhaust slimmer and providing better engine performance and reduced noise. The four-stroke silencers feature a new canister profile and end cap as well as a reworked internal design. Best of all, there is a slip-fit split between head pipe and mid-pipe that allows the exhaust system to be removed without having to remove the shock first. 2019 Cooling System All 2019 KTM model feature newly designed radiators which are mounted 12mm lower than the predecessors. This lowers the center of gravity and in conjunction with a new radiator shape they match perfectly with the design of the new radiator shroud to make the bike narrower and easier to get forward on the bike. Thanks to calculated liquid circulation (CFD) and improved air ventilation cooling is improved. The coolant tube, that passes through the frame, is 4 mm larger to improve coolant flow from the cylinder head to the radiators. DIRT & TRAIL MAGAZINE JULY 2018 19