KTM: 2011 KTM 250 SX-F Dirt Bike Motorcycle

KTM: The 250 SX-F is nearly a guarantee for top positions in hard fought Motocross-events. That is proven by numerous top places at MX2 World Championship.

KTM Dirt Bikes, Ktm Motorcycles, ktm, 2011 ktm 250 sx-fAlready known for its strong performance, the new generation presents itself with a further developed, stronger engine including fuel injection and the option to include an electric start with small effort.

The new 250 SX-F will remain a winning bike that will be hard to follow for the competitors.

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 development of the 350 SX-F, 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 un-reached level with the 350 SX-F and therefore build the ultimate winning bike for the motocross future.

Through the cooperation of Stefan Everts and KTM, a new milestone in motorcycle development has been set.

The lightweight 350 SX-F with extremely compact DOHC engine makes the perfect weapon for every motocross use. Performance close to the 450cc motocrosser means no loss at starts or during acceleration, handling that is close to the 250cc bikes due to compact measurements and low gyroscopic masses.

With this combination of powerful power delivery and playful handling the rider benefits more, the longer a race goes on – no matter if professional or beginner. Additional ingredients like electric start and electronic fuel injection make the 350 SX-F the ultimate contender at MX1 class.

KTM has experience in building sport motorcycles for more than 55 years.

This shows the highest level of experience in developing race bikes. 170 world championship titles prove this.

Frame

Completely new frames made of modern lightweight chrome-moly steel material in various profiles. Compared to our 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.

To the aluminum frame trend of our competitors, we have 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.

KTM Dirt BikeRear Suspension

KTM has proven that the PDS rear suspension system is capable of wining any motocross race. But when it comes to Supercross the PDS becomes more critical in regards to bike set-up.

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, or 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 2-stroke bikes and to off-road applications, whereas a high spring progression in the linkage system benefits the extreme Motocross and Supercross applications.

Shock

PDS 2011: Longer PDS shock to offer an improved rising rate character.

Linkage: Completely new WP unit with piston and bushings that 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 hammer and punch.

A wide range of adjustability of rebound and high/-low speed compression damping are KTM standard anyway.

Why 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 centre 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 keep a major weight benefit, also in the future.

CYLINDER HEAD-

The heart of the compact engine is the exceptional cylinder head.

*Dual overhead camshafts

*DLC coated finger followers

*Fluidic developed intake port guarantees 10% more flow and increased performance

CAMSHAFTS-

The newly developed camshafts have new valve timing tailored to the improved gas flow stemming from the new intake port and exhaust.

*New cams improve the torque and overall performance

EXHAUST SYSTEM-KTM 250 SX-F Dirt Bike Engine

A newly designed exhaust header combined with the new silencer includes a bigger outlet diameter that leads to better air flow, improved performance and lower noise emissions.

IGNITION-

The new 250 SX-F engine has an AC generator with bigger capacity that 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 250 SX-F engine is equipped in serial production with a kick starter.

*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

*An optional E-start kit with starter, ignition cover, gears, battery and wiring will be available as a KTM PowerPart

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.

*Temperature and altitude compensation as well as the automated cold start system are state of the art

*An optional KTM PowerPart map select switch with aggressive, standard and soft modes activates additional preset engine mapping

*A KTM PowerPart user setting tool will allow data logging with a laptop and provide the opportunity to change the mapping with a few mouse clicks. The software gives you the possibility to adjust the fuel mixture exactly for every RPM range

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