The KTM 450 SX-F nearly won Dirt Rider’s 450 MX Shootout last year, finishing in the runner-up spot with its strong but usable powerband, good suspension, and nimble handling. For 2019, KTM made several changes to the engine, suspension, and chassis, similar to those found on last year’s Factory Edition model. The stiffer frame, updated suspension settings, narrower chassis, and more agreeable ergonomics were all improvements, but mellow bottom-end power delivery made the bike feel heavy on the track, despite its being the lightest bike in the test at 234 pounds. The 2019 450 SX-F is an improvement over last year’s model in most areas, but the bottom-end power left something to be desired. Combine that with the fact that the other bikes have also continued to improve, and the KTM slid to fifth place in this year’s standings.
Video By: Bert Beltran
The 450 SX-F engine features a slew of changes for 2019 including a more compact cylinder head that is 15mm lower and 500 grams lighter than the 2018 model. There’s also a new exhaust system, a Pankl transmission, a new 44mm throttle body, updated ECU maps, a reworked airbox, and revised traction control and launch control settings.
We mounted a Dunlop D404 street tire on the rear wheel and ran the bike on our in-house Dynojet dynamometer, where it produced 50.79 hp at 9,320 rpm and 32.55 pound-feet of torque at 6,800 rpm. With those numbers, the 450 SX-F ranks fourth among the six bikes in both the horsepower and torque categories. We then mounted a fresh set of Dunlop MX33 soft-to-intermediate-terrain tires to ensure consistency in traction among the six competitors through the duration of the test.
The KTM engine has a very smooth power delivery that makes it deceivingly fast. It’s easy to ride but doesn’t have much of a bottom-end hit, which makes it feel sluggish from a low rpm. This has an effect on how the 450 SX-F rides. Despite being the lightest bike in the test at 234 pounds filled with fuel, it feels heavier than some of the other bikes that weigh more. There’s also a noticeable amount of vibration at low rpm that dissipates at about quarter throttle. The engine comes alive in the midrange and top-end, and revs to the moon while continuing to pull. It shifts smoothly as well, and the Brembo hydraulic clutch is easy to pull in and doesn’t fade under heavy use. The engine is also pleasantly quiet.
The KTM has two maps that can be changed via the switch on the left side of the handlebar. It also has traction control, which can be used in either map. Map 1 offers slightly more bottom-end power while map 2 delivers more top-end and over-rev along with improved torque feel from the midrange to the top-end. Traction control mellows out the power delivery, and we found it worked best on map 2.
The 450 SX-F is equipped with a WP AER 48 air fork and WP shock, and KTM updated the components to match the new chassis for 2019. Both fork and shock get new new damping settings and the latter features an updated main piston.
The fork offers lots of adjustability with air pressure, compression, and rebound. It has a plush feel throughout the the stroke, but feels a bit bouncy with the stock clicker settings, especially on slap-down landings. Slowing down the rebound fixes this, and it also helped the front end track better during braking bumps and cornering. Test riders went in on the rebound between four and eight clicks depending on the track conditions and were pleased with the results.
Having the ability to adjust the fork air pressure was advantageous. Lighter test riders ran less pressure, down to 10.2 bar, while faster, heavier test riders went as high as 10.8 bar. The shock took less adjustments to dial in than the fork with only a few test riders going in on rebound and high-speed compression. Overall, the WP suspension on the KTM is good but not as plush or comfortable as the Kawasaki or Yamaha in stock form. Fortunately, it’s the most adjustable. With some time and testing, it can get fairly close.
The 2019 450 SX-F gets a new, stiffer black frame, a more rigid upper triple clamp, and a revised swingarm that has a longer slot for the rear axle. The subframe is now 40mm longer, and the redesigned radiators are 12mm lower than the previous model. Designers also resculpted the fuel tank for better ergonomics, and there’s new bodywork and a reshaped seat to match.
The KTM is one of the best-handling bikes in the class. It’s very neutral, balanced, corners well, and has good stability. The increased rigidity allows it to change direction quicker than the previous year model, yet it remains stable in a straight line.
The 450 SX-F is easy to move around on thanks to its ever-improving ergonomics. The rider triangle of the seat, handlebar, and footpegs are very comfortable too. Like the Husqvarna, the KTM has the strongest brakes in the class with the Brembo components in the front and rear. The two also share the excellent ODI lock-on grips.
Why It Should Have Won
It has a neutral-handling chassis, the strongest brakes, a hydraulic clutch, and is the lightest bike in the class.
Why It Didn’t Win
The engine has a mellow bottom-end power delivery and lacks excitement, both of which make the bike feel heavier than it really is. Also, the stock suspension doesn’t match the comfort or performance of the Kawasaki and Yamaha.