2011 KTM SX MODELS
The new KTM SX generation means a completely new chassis–including a new frame–and, on the four-strokes, a linkage rear suspension and completely new bodywork. As a highlight, KTM presents the newly developed, DOHC, four-stroke engine with 350cc, fuel injection and electric start. The new SX generation contains the concentrated know-how of a highly modern development department combined with the knowledge of a racing department, which has been very successful for many years and led by 10-time World Champion Stefan Everts. Since the beginning of the 350SX-F’s development, Stefan was at the leading edge and stamped his baby from the very first sketch until the final serial settings. His ambitious aim was to lift the motocross topic to a new, previously unreached level with the 350SX-F and, therefore, build the ultimate winning bike for the motocross future.
CHASSIS SX MY 2011
Frame
The all-new frames are made of modern lightweight chromoly steel material in various profiles. Compared to previous SX frames, the MY 2011 frame design provides higher torsional and reduced longitudinal stiffness. In addition, it is designed to absorb energy created from the rear wheel impacts. This new design benefits both the PDS of the new two-strokes and Pro-Lever Linkage rear suspension of the four-strokes. The basic frame designs are pretty much the same. The main difference between PDS and linkage is the tower of the upper shock mount, which for both systems takes the main role to isolate the shock absorber forces from the frame. KTM has delivered a high-tech steel frame that weighs less than the lightest competitor. In addition, it is easier to maintain, easier to work on and supplies more space for the tank and other components.
Rear Suspension
KTM has proven that the PDS rear suspension system is capable of winning any motocross race. But when it comes to Supercross, the PDS becomes more critical in regards to bike setup. The linkage provides a better solution to the increased loading demands that extreme Supercross requires and covers a wider range of circuits.
Both systems have a certain rising rate, which means that when the rear wheel moves at a constant rate, the rate of the shock shaft increases; in other terms, if the rear wheel travels at a constant velocity, the shock shaft is accelerating. The difference between the two systems is, with PDS the shaft velocity does not increase as much as with linkage. The PDS system creates additional damping with internal systems in the shock, and as a result, both the linkage and PDS system produce similar dampening characteristics. The main difference, then, lies in the fact that the PDS system provides a more linear spring progression than the linkage system. The PDS character is extremely beneficial for the lighter two-stroke bikes and to off-road applications, whereas a high spring progression in the linkage system benefits the extreme motocross and Supercross applications.
PDS 2011: A longer PDS shock will offer an improved rising rate character.
Linkage: A completely new WP unit with piston and bushings will provide better seal and friction properties to handle the higher shaft velocities. Both shocks also have a new spring retention and preload system to allow for preload adjustment without the use of a hammer and punch.
PDS for the two-strokes
The directly linked PDS shock has turned out to be the best solution for the two-strokes. Two-strokes have a totally different engine characteristic than four-strokes and also a different center of gravity. Many tests have proven that the PDS rear suspension fits better to the lighter and more nervous characteristics of the two-strokes. With the lighter PDS system, the two-strokes will continue to have a major weight advantage. The majority of the Enduro applications benefit from the more linear spring progression of the PDS. In addition, it provides a better ground clearance, less maintenance, less weight and easy access to remove the shock from the bike within a few seconds.
Swingarm
New cast aluminum swingarms for both the PDS and the linkage. The single-component casting process allows unlimited geometry solutions and eliminates any inconsistencies created by welding. Updated mounting positions, higher profiles and optimized flex are supporting the frame and suspension characteristics.
Front suspension
All SX models are fitted with the latest generation of 48mm USD front forks made by WP in Austria. Due to intense development in the recent years, the WP closed-cartridge technology has been fine-tuned for excellent sensitivity and damping characteristics. For the MY 2011, new settings for each model perfectly match the needs of new chassis packages. Due to an internal closed damping cartridge, these forks create more consistent damping characteristics in extreme use situations than open-cartridge systems.
Triple clamps
The KTM-patented SX triples are CNC-machined out of high-quality aluminum. The design and clamping avoid squeezing the tubes and support fork action. In addition, the design provides a certain flex, which allows the triple clamps to follow the fork legs when deflected during hard landing or braking.
Airbox
The new layout of the airbox was driven by two main functions: optimized protection for the air filter against dirt and maximum airflow for maximum performance. Due to the special design between the filter and intake throttle body, the airbox was designed separately for every displacement and improves the power significantly. The ability to change the large Twin-Air filter quickly and without tools is the KTM standard.
Exhaust silencer
The four-strokes have new, improved silencers that score points with a modern and voluminous profile, not only optically but also reducing the noise level to future noise emission regulations (115 dB(A)).
A bigger outlet diameter improves the performance and delivers a sound improvement. New silencers for two-stroke bikes introduce a new ‘two-component’ technology. A strong plastic holder is injection-molded around the aluminum housing to attach the silencer to the motorcycle better.
Cooling system
The proven integrated cooling system routes from the cylinder head through the frame triangle directly to the radiators, and the removed tubing simplifies the radiator mounting and improves the airflow through the radiators. A new T-connector with an optimized fluid flow improves the heat dissipation.
Tank
The slim 7.5-liter tank made from lightweight polyethylene includes a compact fuel pump on 250/350SX-F models. All other models introduce a new fuel tank with the same capacity as well. The well-proven 1/4-turn fuel cap allows easy and quick refilling and includes protection against unwanted turning. The fuel cap can be released by simply pressing the orange inner segment of the cap.
Brakes
Brakes by Brembo are serial equipment of KTM models and are combined with lightweight wave rotors, which are the benchmark when it comes to feel and brake performance.
Engine
Already known for its strong performance, the new generation presents itself with a further developed, stronger engine including fuel injection and the option to include electric start with little effort.
Cylinder head
The heart of the very compact engine is the brilliant cylinder head with two overhead camshafts and DLC-coated finger followers. A fluidic-developed intake channel guarantees more flow and, therefore, increased performance.
Camshafts
Newly developed camshafts have a new valve timing, which is tailored to the improved intake charge due to the new intake port, shape of the intake boot (between throttle body and air filter) and the new exhaust. The new cams supply a better cylinder filling and, therefore, improve the torque and performance delivery.
Exhaust system
A newly dimensioned exhaust header combined with the new rear silencer with bigger outlet diameter leads to a better flow and therefore an improved performance.
Ignition
The new 250SX-F engine has an AC generator with a bigger capacity, which runs in oil. This new generator secures enough energy for the fuel injection system and allows the retrofitting of an electric start system.
Starter
The new 250SX-F engine is available in serial production only with a kick-starter to keep the weight at a minimum level. A new capacitor (attached to the throttle body) in combination with the fuel injection system ensures that the bike can be started easily and safely without a battery. Additionally, the new engine gives the option to retrofit an electric start system with small effort. An E-start kit with starter, ignition cover, gears, battery and wiring will be available in the PowerParts program.
Engine Management System (EMS)
The newly developed engine management system by Keihin with electronic fuel injection and 42mm throttle body secures spontaneous and powerful response and maximum performance. Comfortable temperature- and sea-level compensation as well as the automated cold start system are state of the art. Time-consuming rejetting of carburetors or engine stalls at fast throttle openings is a thing of the past. An optional map select switch (PowerParts) activates additional engine characteristics with the click of a switch. Additionally, the user setting tool (PowerParts) allows the logging of data of the bike with a laptop and to change the mapping by few mouse clicks.
Engine
Ultra-compact four-stroke engine with modern electronic fuel injection and electric start. The extremely short-stroke 349.5cc, DOHC engine with 57.5mm stroke and 88mm bore has a very wide, usable speed range, top performance and very efficient rideability. The layout of the 350 engine is close to the 250SX-F engine and has insignificantly bigger dimensions at nearly the same weight. The playful handling similar to a 250 engine results mainly from reducing the rotational masses to a minimum.
DOHC cylinder head
Four ultra-lightweight titanium valves in combination with DLC-coated finger followers allow a high rpm limit of 13000rpm. Herewith, the engine can deliver enough power to win every holeshot.
Valvetrain
The crankshaft turns an intermediate gear, which drives the cam chain and, at the same time, acts as balancer shaft and holds the water pump. A hydraulic cam chain tensioner secures a reliable tension of the chain and, therefore, precise cam timing.
E-start
A few years ago, KTM proved that an electric start in motocross is of great advantage. Therefore, the new 350SX-F can also be started easily by the press of a button. For non-believers, the 350SX-F has an option to retrofit a kick-starter to the bike. The following variations are possible: only E-start; E-start plus kick-start; only kick-start.
Engine Management System (EMS)
The newly developed engine management system by Keihin with electronic fuel injection and 42mm throttle body secures a spontaneous and powerful response and maximum performance. Temperature and sea level compensation as well as the automated cold start system are state of the art. Time-consuming rejetting of carburetors or engine stalls at fast throttle openings is a thing of the past.
An optional map select switch (PowerParts) activates additional engine characteristics by the click of a switch. Additionally, the user setting tool (PowerParts) allows the logging of data of the bike with a laptop and to change the mapping by a few mouse clicks.
Balancer shaft
For balancing the rotational masses, the 350SX-F engine has a balancer shaft on the right side of the engine, which acts at the same time as a water pump intermediate gear and drive pinion gear for the camshaft. This solution secures a very compact overall design of the engine.
Transmission and clutch
The newly developed five-speed gearbox was designed to suit the engine characteristic of the 350SX-F and shines with a very precise shifting. The hydraulic clutch by Brembo guarantees a light operation and good controllable modulation of the clutch.
Lubrication system
The new 350SX-F engine has two oil pumps similar to the 250SX-F engine. A pressure pump supplies the crankshaft, piston and valvetrain. Additionally, it supplies lubrication for the clutch and cools the ignition. A suction pump evacuates the crank housing and lubricates the gearbox. This creates a vacuum in the crank housing to increase the engine performance.
Engine
If asked for maximum power, there is no other option but the 450SX-F. For years, this bike has been synonymous with maximum power. The well-proven DOHC engine has only slight changes, as it was continuously developed over the last few years and could win numerous shootouts. The package for 2011 with a new chassis will be able to play its strengths even better.
Carburetor
The engine of the 450SX-F is powered by a Keihin FCR flat throttle carburetor with 41mm. The integrated acceleration pump secures a spontaneous and powerful performance.
Clutch
The 2010 refined clutch has a strengthened design of the basket and can withstand the high power delivery of this engine. The hydraulic clutch operation is of the highest KTM standard as well.
Gearbox
The five-speed gearbox developed for 2010 was well-accepted on the market. The slightly closer ratio between the gears suits most of the tracks perfectly. The five-speed gearbox is an essential part for the good results in the comparison tests.
Exhaust header
The super-light titanium exhaust header pipe and the innovative Header Pipe Resonator System (HPRS) guarantee, combined with the new rear silencer, top engine performance at very low noise level.
E-starter
The fact that an electric start can be of enormous advantage during a motocross heat has spread around and was highlighted in all shootouts. The minimal disadvantage of an increase of 1.5 kg is less problematic than the loss of positions when the bike has to be restarted by kick-start after a minor slip-up. Stefan Everts was skeptical at the beginning, but today he says, ‘I would not want to ride a bike without E-start again; doesn’t matter if at racing or just for fun!’
The 125SX boasts minimum weight and reasonable cost of acquisition and maintenance. The known high-engine performance of the 125SX KTM could again be increased for 2011, which will secure the sympathies especially of young future champions.
News MY 2011:
* New chassis (PDS)
* Improved rear silencer
* New airbox
* Airflow optimized intake boot between filter and carburetor
* Noticeable increase in power performance
News MY 2011:
* New chassis (PDS)
* Improved rear silencer
* New airbox
* Airflow optimized intake boot between filter and carburetor
* Noticeable increase in power performance
For years, KTM has committed to the development of two-stroke engines which are an advantage against four-strokes in many aspects. The power-to-weight ratio is unbeatable, as is the lower cost of acquisition and maintenance, and they are simple to service and rebuild, which allows a piston change without having studied engineering.
News MY 2011:
* New chassis (PDS)
* New airbox
* Airflow optimized intake boot between filter and carburetor
* New exhaust (new shape, bigger diameter at connection pipe)
* New two-component rear silencer (better connection, bigger inner diameter)
* Newly developed cylinder (lower exhaust port, new timings, optimized exhaust control)
* Noticeable increase in power performance
* Higher torque
* Better rideability
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