A new Keihin 44mm throttle body and engine management system provides excellent response and performance. The cable system is a direct-connect design without linkage to the throttle body, further improving rider feel and features cable adjustment at the throttle tube housing, not down at the throttle body like before. No, that isn’t a two-stroke pipe, it is the Flow Design Header, developed to increase power, throttle response and maintain low noise levels. The muffler is now 40mm shorter and, with its new mounting point, the muffler is 60mm closer to the center of the bike.
The all-new chromoly frame is lighter, featuring 20% increased torsional rigidity and 30% decreased longitudinal stiffness. These changes help the frame absorb the energy created from the rear wheel loads and improve overall handling. The head angle is also steeper and the wheelbase is 12mm shorter. New laterally-attached engine stays connect to the back of the cylinder head, helping reduce vibration and working with the frame changes to provide optimal flex. The new subframe is smaller and 250 grams (0.55) pounds lighter, contributing to the 10 pound overall weight savings.
The WP 4CS forks feature revised damping settings, while the WP shock is all new to compliment the new frame. The shock features a new body with a larger reservoir and a new piston and shock shaft. A new clevis contributes to a 12mm shorter overall shock length and lighter weight. Even with a shorter shock, rear wheel travel is increased by 10mm thanks to longer pull rods and a new linkage system. The shock spring rate dropped significantly due to the changes.
Leaving nothing untouched, even the WP radiators are new, improving engine cooling by 10%. The redesigned radiator guards improve air flow and increase structural strength significantly. Adding to the overall 10 pound weight savings is a 2.2 pound lighter Lithium-ion battery and a simplified wiring harness that also reduces weight and improves maintenance. A lighter airbox is home to a radically different TwinAir air filter. The filter mounts on a cage that features a simple design, which minimizes incorrect installation of the filter to the cage and installation of the cage into the airbox. It is a quick install system, even easier than previous KTM models. Staying true to the weight loss diet, even the footpegs are lighter, as is the shifter.
Three different engine maps – soft, standard and aggressive – are available via the map select switch on the handlebar. The aforementioned gear position sensor allows the engine maps to change based on the gear position and the baseline engine map setting. The same switch can be used to access KTM’s version of launch control.
ON THE TRACK
The 2015 450 SX-F Factory edition feels completely different from the moment you swing a leg over it. The seat and handlebar position are both 10mm lower and the footpegs are now mounted 5mm back and 4mm down.
It only took a lap to figure out that KTM may have created one of the best 450F engines to date. It’s an amazing powerplant with ultra smooth delivery. The electric-like off-idle power builds into a meaty mid and then continues to deliver arm-stretching power seamlessly all the way to the 11,500 rpm rev limiter. The 450SX-F Factory Edition flat out rips! The impressive engine allows riders to lug and grab traction in slippery conditions, or let it rev and ride it aggressively. It’s an engine that caters to every style of riding, with tons of torque. The engine changes and rubber-mounted handlebar mounts have also helped reduce vibration.
This is the lightest production 450F motocross bike and that translates into an ultra-flickable machine. Quick direction changes and mid-air adjustments feel like you are riding a 250F, not a 450. Thanks to the smooth power delivery, combined with the chassis changes, the 450SX-F Factory Edition corners better than any KTM to come before it. After our day at Cahuilla Motocross track we feel the Factory Edition just might be one of the best cornering bikes in the class. Enter a corner and enjoy the ride! The Factory Edition doesn’t knife under or stand up mid corner, it lays over and goes where you aim it. It makes diving to the inside fun.
- 10 Pounds Lighter
- Light and nimble handling
- Smooth and torque power delivery
- WP Fork still a bit harsh in the mid stroke
- Aggressive seat cover
The suspension revisions give the 450 Factory Edition a balanced feel and help contribute to its great cornering characteristics. The shock and linkage changes help keep the bike hooked up during acceleration, even in choppy terrain. While the damping revisions improved the feel of the WP 4CS and reduced some of the previous mid-stroke harshness, there is still room for improvement. The suspension favors riders over 175 pounds who like to ride aggressively or in loamy conditions. Lighter and slower riders will want a little more plushness and comfort out of the suspension, especially in choppy conditions.
Overall handling and performance of this latest 450 SX-F are a big improvement over the non-factory edition. We can’t wait to hit more tracks and spend more time enjoying the lightest 450 motocross machine ever produced.