Best Motocross Bike 2nd Place—2021 KTM 250 SX-F

Hugh Janus · December 18, 2020

As the bike that began and set the standard for the current trend of high-revving, high-horsepower 250 four-stroke motocross bikes, the KTM 250 SX-F still reigns as king of the class in terms of raw horsepower while producing some of the best torque figures. Combine that with its improved suspension settings and proven chassis, and you have a well-rounded package right out of the box. Perhaps the KTM’s only perceived shortcoming is that its high-rpm powerband naturally suits those who ride aggressively, which happens to mostly be riders and racers of intermediate to pro level in skill. And while that can also be said of the three other bikes that finished behind it, the 250 SX-F is still the second best bike in terms of low-rpm power and torque feel, which is one of the reasons it finishes in front of them.

“The KTM 250 SX-F is an expert’s motorcycle that has widespread gear ratios and requires revs to make it go anywhere, but it is approachable to the everyday rider.” —Michael Gilbert (Jeff Allen/)

In fact, the only machine that is ranked in front of it has more low-end grunt and is now a competitor in the high-rpm horsepower battle—the combination of which enables it to be ridden easier and more effectively by lower level riders who aren’t willing or don’t want to go for broke with their throttle hand, while also being given the nod by intermediates and pros alike. It’s close at the top of the 250F motocross bike class, and although the KTM 250 SX-F didn’t take the victory this year, it is still an excellent choice for riders far and wide, especially those who fit the bill for its engine characteristics.

Hitting the scales at 232 pounds, the 250 SX-F is the lightest bike in the class. (Jeff Allen/)

2021 KTM 250 SX-F Engine

Like it has in years past, the 250 SX-F performed superbly on the dyno with 41.1 hp at 13,700 rpm and 19.1 pound-feet of torque at 9,100 rpm, which gives it the most peak horsepower in the class and the second most peak torque.

The KTM is the king of the dyno in the 250 four-stroke motocross bike segment once again. Its 41.1 hp at 13,700 rpm is the highest peak figure in the class, while 19.1 pound-feet of torque at 9,100 rpm puts the orange machine at just 0.2 pound-feet less at peak than the Husqvarna FC 250. (Michael Gilbert/)

Sharing the same engine as the Husqvarna FC 250, the 250 SX-F follows a similar horsepower curve to its Austrian counterpart with both bikes producing the most horsepower in the class from 5,200 to 8,200 rpm. The Austrian duo are matched by the Honda CRF250R from 8,200 to 8,400 rpm and surpassed by it from 9,700 to 10,800 rpm. The 250 SX-F and FC 250 make more horsepower than the KX250 and YZ250F from 4,800 rpm on up.

The 250 SX-F produces just a touch more horsepower than the FC 250 from 6,100 to 6,500 rpm, 11,000 to 11,500 rpm, 11,900 to 12,400 rpm, and 12,700 rpm until peak. The only area along the horsepower curve the 250 SX-F is down from the FC 250 is a minor amount from 8,800 to 9,800 rpm. The 250 SX-F also makes its class-leading 41.1 peak horsepower at the highest rpm of all the bikes.

Related: 2020 KTM 450 SX-F Factory Edition Review First Ride

As far as torque, the 250 SX-F again follows a similar curve to the FC 250 with the only minor exception being their peak figures. Although the Austrian duo produce their highest number at 9,100 rpm, the 250 SX-F spins just 0.2 less pound-feet at peak than the FC 250. Another notable point is that the 250 SX-F cranks out slightly more torque from 13,000 rpm to peak.

Compared to the Japanese bikes, the 250 SX-F makes more than the KX250 and YZ250F from 5,200 rpm on up and is only matched by the CRF250R from 8,000 to 8,400 rpm and is superseded by the red bike from 9,500 to 10,600 rpm. After following a similar curve to the CRF250R until 11,600 rpm, the 250 SX-F is unmatched by any of the Japanese bikes from that point until peak.

Related: Best Motocross Bike 3rd Place—2021 KTM 450 SX-F

On the track, the 250 SX-F doesn’t have the strongest low-end power, but it does have the second most behind the YZ250F. From there, it only gets better as the rpm increase. The engine pulls seemingly forever and never signs off. When it does reach the rev limiter, it doesn’t hit a proverbial wall and lose power; it just keeps pulling and maintains momentum until the rider grabs another gear. The 250 SX-F ties the FC 250 for the second best torque feel in the class as it doesn’t offer as much as the class-leading YZ250F, but does possess more than the KX250 and CRF250R. For that reason, if the rider misses a shift or selects the wrong gear, it gets back into the meat of the power quicker than the red and green bike, but not nearly as swiftly as the YZ250F.

Other factors that play into the 250 SX-F, and the FC 250 for that matter, having less low-end grunt and rpm recovery than the YZ250F are the Austrian bikes’ gear ratios and the gearing itself. Because the gear ratios are long, it makes gear selection more crucial to using their power effectively. The best strategy is to ride each gear as long as possible, ideally until coming close to or actually hitting the rev limiter, then finally upshifting. Also, the 250 SX-F and FC 250 come with fairly tall 14/51 gearing. Taking all of that into account, some test riders commented that they would consider adding a tooth or two to the rear sprocket or even trying a 13-tooth countershaft sprocket to liven up the bottom-end power and make gear selection less critical.

2021 KTM 250 SX-F Suspension

Updates to its WP Xact air fork and WP Xact shock along with the addition of new low-friction linkage bearing seals made by SKF are the mechanical changes the KTM 250 SX-F enjoys for 2021. (Jeff Allen/)

KTM makes changes to the suspension setup of its motocross bikes each year, and the 2021 250 SX-F features the best suspension setting it has had since the latest generation was introduced in 2019. The WP Xact air fork and WP Xact shock have somewhat of a springy feeling while sitting on the bike, but have decent rebound control while riding. The WP components are also more progressive than ever with a fairly supple feel in the initial part of the stroke combined with impressive bottoming resistance.

“The WP Xact suspension components on the KTM are plush. They soak up all bumps very well, yet hold up great over big landings and deep in the stroke.” —Tanner Basso (Jeff Allen/)

The stock settings are tunable, and although many test riders set the sag and left the clickers alone for the most part, a few others noted improvements to the fork by increasing the air pressure from the stock 10.5 bar to 10.7 bar, which offered more holdup and comfort and helped reduce pitching. The shock settings are also very close in standard trim. Some test riders opted to raise the sag from the recommended 105mm up to 103mm and added anywhere from a quarter to a half turn on the shock’s high-speed compression to help pick up the rear of the bike, which rides just a little low in the stroke. Both of these adjustments improved the shock’s comfort and reduced the chassis’ slight chopper stance.

2021 KTM 250 SX-F Chassis/Handling

“The KTM chassis feels much more lively than the Husqvarna’s, meaning it takes time for the bike to settle into the corner and rip out. It turns well, and in combination with its easy power delivery, makes for an easy motorcycle to ride. Like the Husqvarna, the KTM has a ton of braking power that quickly brings it to a stop.” —Michael Gilbert (Jeff Allen/)

With its light and nimble feel on the track, the 250 SX-F is one of the easiest bikes in the class to maneuver. That can partially be attributed to the fact that it is indeed the lightest 250F motocross bike at 232 pounds. It is plenty stable at speed and corners well, and some test riders commented that it is also the most effortless to corner while standing. The orange machine’s slight chopper feeling is decreased by setting less shock sag and its cockpit is large and roomy, assisted by the wider than usual Neken handlebar.

Test riders noted that if the 250 SX-F were their personal bike, instead of cutting the stock handlebar by 4–5mm on each side to give it a more traditional width like those that come standard on the Japanese models, they would instead prefer to invest in a different handlebar altogether such as a Renthal Fatbar or ProTaper Evo for more flex and comfort. Narrow bodywork and a sit-on feeling contribute to the KTM’s racy feeling as well. Like all of the Austrian brand’s full-size motocross bikes, the 250 SX-F features Brembo brakes, which are the most powerful in the class. Test riders also praised the bike for its comfortable seat and excellent ODI lock-on grips.

“Although it doesn’t have a ton of initial hit, the 250 SX-F has a very smooth yet aggressive pull when transitioning from the bottom-end to the midrange, and then continues to pull all the way up to the top-end. Also, the Brembo hydraulic clutch is great! It has an awesome feel and doesn’t fade.” —Tanner Basso (Jeff Allen/)

Why the 2021 KTM 250 SX-F Should Have Won

It has a strong, fast engine that makes the most peak horsepower, an improved suspension setup with good base settings, a neutral-handling chassis, agreeable ergonomics, the best brakes, an awesome Brembo hydraulic clutch that provides a positive and consistent feel at the lever, and is the lightest bike in the class.

Why the 2021 KTM 250 SX-F Didn’t Win

The 250 SX-F has less low-end power, torque feel, and suspension comfort than the YZ250F.

“The 250 SX-F is narrow, has a little bit of a chopper feeling, and feels like a longer wheelbase bike. The front and rear wheel seem to track in line versus a hinged feeling that I recall from the previous year model.” —Allan Brown (Jeff Allen/)

Gearbox

Helmet: Shoei VFX-EVO

Goggle: 100% Racecraft

Jersey: Fly Racing Lite

Gloves: Fly Racing Lite

Pant: Fly Racing Lite

Boots: Sidi Crossfire 3 SRS

Source