Find out how much power these popular dirt bike models from Husqvarna, Kawasaki, Honda and Yamaha make in 2021!

By Andrew Oldar / dirtrider.com

2021 Husqvarna FC 250

As it has in years past, the Husqvarna FC 250 features one of the best engines in the 250 four-stroke motocross bike segment for 2021. It is a little bit smoother throughout the rpm range than the 2021 KTM 250 SX-F, which largely has to do with its airbox receiving less airflow than its orange counterpart. Although the FC 250 comes with an optional ventilated airbox cover, its six slit-shaped vents aren’t as large or as plentiful as the 10 perforations on the 250 SX-F’s. The good news is that you can take your trusty drill and add some holes to the FC 250′s airbox cover to make it run more like the KTM.

Despite its less aggressive nature in comparison to the 250 SX-F on the track, the FC 250 engine makes just about the same amount of power as the KTM along the majority of the rpm range on the dyno. It actually produces more horsepower than the 250 SX-F from 8,800 to 9,800 rpm and a touch less from 11,000 to 11,500 rpm and 11,900 to 12,400 rpm. The 250 SX-F begins to ascend higher on the curve at 12,700 rpm until it makes its peak horsepower of 41.1 at 400 rpm higher than the FC 250. At peak, the 2021 Husqvarna FC 250 cranks out 40.3 hp at 13,300 rpm and the most in-class torque with 19.3 pound-feet at 9,100 rpm.

“Even in the aggressive map 2, the 2021 Husqvarna FC 250′s power delivery is very smooth initially and begs to be opened up. The coolest part about the delivery is that it is so smooth and builds power throughout the rpm, but really comes alive and lets you wind it out.” — Michael Gilbert

2021 Husqvarna FC 250 Engine Specifications

Type:	Liquid-cooled, DOHC, four-stroke single-cylinder; 4 valves/cyl.
Bore x Stroke:	78.0 x 52.3mm
Displacement:	250cc
Compression Ratio:	14.4:1
Fuel Delivery:	Electronic fuel injection

2021 Kawasaki KX250

Although the Kawasaki KX250 enjoyed a plethora of engine updates last year despite the fact that the powerplant itself didn’t look all that much different on the outside, Team Green’s 250 four-stroke motocrosser received even more changes for the 2021 model year including electric start, a revised crank web, 3mm-longer connecting rod, different combustion chamber design, flatter piston crown, a higher spring rate for the outer valve springs, 2mm-wider cam chain, revised cylinder water jacket, thicker cylinder wall, updated ECU settings, and a coned disc-spring hydraulic clutch. Also, the exhaust cam timing was retarded three degrees, the rev limit was increased by 350 rpm, and the intake and exhaust port throats feature a larger diameter.

Compared to last year’s model, the 2021 Kawasaki KX250 makes slightly less horsepower from 4,000 rpm to 6,200 rpm, nearly matches it from that point to 7,600 rpm, then loses ground to the prior year bike from that engine speed to 13,000 rpm, where it surpasses the 2020 model from that point until hitting its 14,500-rpm rev limiter. Both bikes make the same peak horsepower figure of 39.6, but at different points along the curve. While the 2021 machine makes it at 13,200 rpm, the 2020 model produces it at 12,400 rpm.

The torque curve tells a similar story. The 2021 KX makes less torque than the 2020 model from 4,000 rpm to 6,200 rpm, comes close to it until 7,600 rpm, then falls short again until matching it at 11,400 rpm before getting overtaken by its year-old brother a final time from that point until 12,800 rpm, where it surpasses the 2020 bike until hitting maximum rpm. Churning out 18.4 pound-feet of torque at 9,400 rpm, the 2021 KX250 makes 0.5 less pound-feet of torque at peak than the prior year bike.

“The 2021 Kawasaki KX250 revs quickly, has an aggressive yet rideable power, and is very loud at high rpm. Also, the new Nissan hydraulic clutch is very nice!” —Tanner Basso

2021 Kawasaki KX250 Engine Specifications

Type:	Liquid-cooled, DOHC, four-stroke single-cylinder; 4 valves/cyl.
Bore x Stroke:	78.0 x 52.2mm
Displacement:	249cc
Compression Ratio:	14.1:1
Fuel Delivery:	Electronic fuel injection

2021 Honda CRF250R

As the first bike to go after the KTM 250 SX-F’s high-rpm, high-horsepower engine back in 2018 when its powerplant was new from the crank up, the Honda CRF250R enjoyed changes in 2019 and 2020 that brought back some of the low-end to midrange power it was known for on prior-generation models.

Although Honda has done a commendable job of improving the current-generation CRF250R’s low-end grunt, it still lacks torque throughout the rpm range compared to the other bikes in the class. So long as you keep the rpm high whether by maintaining your momentum, fanning the clutch, or a combination of both, Honda’s 250 four-stroke powerplant can be competitive—it just takes more work and skill to ride fast than most of the other bikes in the class.

On our in-house dyno, the CRF250R produces more horsepower than the KTM 250 SX-F, Husqvarna FC 250, Kawasaki KX250, and Yamaha YZ250F from 9,700 to 10,800 rpm and makes competitive torque figures from 8,000 rpm on up. In terms of peak numbers, the 2021 Honda CRF250R churns out 39.0 hp at 12,900 rpm and 18.8 pound-feet of torque at 9,500 rpm.

“The 2021 Honda CRF250R has a very smooth initial throttle response and low-end, which might be too smooth for faster, more aggressive riders, but I appreciate it for more reasons than one. It offers a lot of confidence to roll onto the throttle aggressively without the worry of spinning, plus it plays well in slick conditions. It is followed by a strong midrange that really wakes the bike up.” — Michael Gilbert

2021 Honda CRF250R Engine Specifications

Type:	Liquid-cooled, DOHC, four-stroke single-cylinder; 4 valves/cyl.
Bore x Stroke:	79.0 x 50.9mm
Displacement:	249cc
Compression Ratio:	13.9:1
Fuel Delivery:	Electronic fuel injection

2021 Yamaha YZ450F

The Yamaha YZ450F is proof that the dyno doesn’t tell the whole story in terms of how powerful a motorcycle is. Although it makes less horsepower and torque than the Honda CRF450R, Husqvarna FC 450, and KTM 450 SX-F from 6,400 rpm until peak on our in-house dyno, the bLU cRU’s flagship motocrosser is the most aggressive and torquey machine in the 450cc category. Luckily, for those who want to tame the YZ450F’s fire-breathing capability in stock trim, the free Power Tuner app can do just that by wirelessly connecting to the bike’s onboard Wi-Fi system, at which point EFI tuning adjustments can be made. As far as peak figures, the YZ450F cranks out 53.1 hp at 9,700 rpm and 32.7 pound-feet of torque at 7,400 rpm.

“Delivering the most hit from the bottom-end to midrange out of all the 450 motocross bikes, the 2021 Yamaha YZ450F actually has too much hit for my liking with the stock map setting. I prefer the Magic (Controlled Acceleration) Map as it works good for all track conditions (morning and afternoon). Still, if you have bad throttle control, you will tire your arms holding onto this powerful bike.” —Cody Johnston

2021 Yamaha YZ450F Engine Specifications

Engine Type:	Liquid-cooled, DOHC, four-stroke single-cylinder; 4 valves/cyl.
Bore x Stroke:	97.0 x 60.9mm
Displacement:	449cc
Compression Ratio:	13.0:1
Fuel Delivery:	Electronic fuel injection