The 2017 KTM 450 SX-F finished second in our annual 450 MX Bike Shootout, bested only by its counterpart: the Husqvarna FC 450. A few months later, the 2017 Factory Edition 450 SX-F was released, but unlike previous FE bikes, it featured only a handful of small refinements: improved suspension settings, a larger, more-powerful battery, and race team-replica graphics. Following tradition, those changes found their way onto the 2018 450 SX-F, and we were lucky enough to throw our legs over the first production 450 SX-F in the States last Friday at Milestone MX Park.
– Updated WP AER48 fork settings, including a new air seal, air piston, and rebound spring on the air leg. The damping fork leg received a new piston. The changes are aimed at increasing low-speed compression and reducing high-speed compression. These changes were implemented on the ’17 Factory Edition bike, and the performance increases were easy to feel on the track.
– To match the look of the factory race bikes, the frame is now painted orange to match the plastic. The plastic frame guards blend in with the frame and protect the finish from the rider’s boots.
– A new, more powerful Sky Rich HJTZ58-FP replaces the Samsung battery of the past. The new cell is larger, but not heavier. Most importantly, it cranks out more power and brings the 450 SX-F to life with more authority.
– Internally, the shift shaft received a new bearing with more overlap for greater durability.
– The radiator louvers have been redesigned to flow more air to the radiators but more importantly, they have been beefed-up considerably and now double as radiator braces as they bolt directly to the frame.
ON THE TRACK
KTM’s David O’Connor delivered our test bike to Milestone MX Park and assisted with the setup for our senior test rider, Rich Taylor. After the usual handlebar and control setup, O’Connor set the sag at 106 mm turned RT loose with the recommended 10.8 bar fork pressure setting. Right from the get-go, Taylor looked comfortable and quick aboard the new SX-F.
As it has been for as long as we can remember, the 450 SX-F is a beast with an abundance of power throughout the powerband. In the Map 1 (standard) setting, the KTM has strong low-end throttle response that pulls strongly into the mid-range with a beefy – yet controllable – surge of power. On top, the power begins to taper off in the upper rpm range and the engine actually makes more noise and vibration than power. Shifting before this point and keeping the bike humming in the middle of the powerband is the most effective. Map 2 yields less low-end power, but the mid-range hit is increased in a big way. Additionally, the bike pulls further in each gear before flattening out. While Map 1 is easier for most riders to make good use of, Map 2 produces more thrills and is the favorite of expert-level riders.
But what about the traction control feature? We’re constantly amused by comments on our social media outlets that scoff at the TC feature, but having lived with it for nearly a full model year now; believe us when we say that in slippery or wet conditions it is magical. When the electronics sense a sudden spike in engine rpm that comes along with a loss of rear-wheel traction, the engine’s power is governed for better grip. Though the sensation is odd at first and feels as if the bike has been slowed down too much, it becomes apparent in short order that the system allows the bike to enjoy improved traction and drive in adverse conditions. Sure, good throttle control is the original traction control, but as it has done in virtually every other aspect of life: technology has made even hooking up easier.
We’re not shy about our dislike for the “new age” air forks that have found their way onto every motocross brand, save for Yamaha. That said, the WP AER 48 fork that graces the KTM (and Husqvarna) motocross bikes stands head-and-shoulders above those offered by Kayaba or Showa. In contrast to other air forks, the WP unit has great comfort in small bumps, good mid-speed control, and excellent bottoming resistance. Action is predictable and consistent, and the front end is easy to adapt to and trust in short order. Our back, the WP shock does an excellent job of absorbing the imperfections in the track’s surface, and as a whole, the KTM 450 SX-F is a great-handling machine. Our only complaint with the stock suspension thus far is a bit excessive front-to-rear weight transfer under both braking and acceleration. Attempting to fine-tune the “pitchiness” out of the suspension package with clicker adjustments proved detrimental to other areas of the fork and shock performance of our ’17 Factory Edition, and the same rings true for the ’18 SX-F. We had good luck with some valving adjustments and a SDI rear linkage last year, and plan to test with both again once this year’s 450 Shootout is concluded.
This weekend, we spent a second full day in the saddle of the 2018 KTM 450 SX-F and came away thoroughly impressed. Though the changes between last year’s Factory Edition machine and this year’s standard SX-F are minimal, the new bike feels livelier and more responsive than our FE, which has close to 65 hours logged on it. Can the new 450 SX-F win the 2018 450 MX Bike Shootout? Though we have yet to ride either of the all-new 450s for 2018 (Suzuki RM-Z45 and Yamaha YZ450F), we wouldn’t bet against it!
Engine: Single-cylinder four-stroke
Bore x stroke: 95 x 63.4mm
Compression ratio: 12.75:1
Valve train: 4-valve DOHC w/ finger followers
Fueling: Keihin EFI w/ 44mm throttle body
Ignition: Keihin EMS
Lubrication: Pressure w/ two oil pumps
Clutch: Wet multi-disc DDS-Clutch w/ Brembo hydraulics
Final drive: 5/8- x 1/4-inch chain
Frame: Chromoly double-cradle
Handlebar: Neken tapered aluminum
Front suspension: Fully adjustable 48mm WP AER air fork; 12.2 inches of travel
Rear suspension: Fully adjustable linkage-assisted WP 5018 BAVP DCC shock; 11.8 inches of travel
Front wheel: 1.6 x 21" Excel
Rear wheel: 2.15 x 19" Excel
Front tire: 80/100-21; Dunlop MX3S
Rear tire: 120/90-19; Dunlop MX3S
Front brake: 310mm disc
Rear brake: 260mm discWheelbase: 58.5 inches
Wheelbase: 58.5 inches
Rake: 26.1 degrees
Triple clamp offset: 22mm
Seat height: 37.8 inches
Fuel tank capacity: 1.85 gallons
Wet weight (approximate, with no fuel): 222 pounds
2018 KTM 450 SX-F | TECHNICAL BRIEFING
2018 KTM 450 SX-4 | FIRST IMPRESSION