We hit the trails on the new KX250X and KX450X off-roaders.
Photography by Drew Ruiz
Kawasaki has long been associated with off-road racing, nothing new there. But what is new is Kawasaki finally offering honest-to-goodness, serious off-road bikes designed to be race-ridden right off the showroom floor. Enter the all-new KX250X and KX450X.
As you probably already know, Kawasaki has a rich history in off-road racing, and the green team has been quite successful at it for decades. You’re probably familiar with names like Roeseler (as in Larry), Davis (as in Ty), Abbott (as in Destry), Strang (as in Josh), and Bell (as in Zach and Robbie), who are all successful racers who have over the years chalked up many big-time off-road race victories, and even championships, while aboard green machinery. The list of famous ultra-fast Kawasaki off-roaders is very, very long. And they all had something in common, besides winning, that their race bikes often started out as KX motocrossers and then modified for off-road use. Strangely enough, despite Kawasaki’s success on the trail, the company hasn’t really offered serious out-of-the-crate off-road race-ready bikes for pros or for hard-core off-road racers. Well, they kinda-sorta did once with the KX450F-based KLX450R in 2007, but the KLX was so tamed down and had put on so much weight in transition that it couldn’t be taken seriously as a racer. Instead, it was basically a very expensive trail bike. So, pros and hard-core Kawasaki off-roaders continued on with their program of building competitive off-road race bikes out of motocrossers. In the U.S., the KLX450R was discontinued in 2010.
Eleven years later, Kawasaki is trying again with the KX250X and 450X. And it doesn’t take a genius to see that Kawasaki seems to have gotten it right this time because what Kawasaki did to these bikes is pretty much the exact same things the pros do to their KX-based race bikes. Now, Kawasaki has done much of the work for them and, better yet, for you, too!
2021 Kawasaki KX250X & KX450X Review | What’s New?
The new KX-Xs are indeed motocrossers slightly tweaked for serious off-roading and racing. One of these tweaks, an important one at that, is an 18-inch rear wheel, which is an expensive modification if you want to do it yourself. Compared to 19-inch wheels, 18-inchers fit tires with larger sidewalls for a smoother ride over rocks and roots, plus better resistance to pinch flats.
Off-roaders tend to like cushier suspensions, too, so both Xs got softer suspension settings front and rear. Very little, however, was changed to either of their powerplants. In other words, they weren’t tamed down at all.
The KX250X is modeled after the all-new KX250, which just came out (usually, an off-road version arrives a year later or so). This means the X model got the same updated features as the ’21 KX250, such as electric starting, a new single coned disc-spring hydraulic clutch, updated brakes, a new frame, and a new engine. The only thing that it didn’t get that the motocrosser did is embedded graphics. (The X’s are still the stick-on type.)
The KX450X, which is nearly a mirror image of the 2021 KX450, also features electric starting and the coned disc-spring hydraulic clutch.
Compared to their motocross cousins, both Xs are fitted with kickstands, more off-road-friendly Dunlop Geomax AT81 tires, skid plates, rear disc brake guards, and one-tooth (51T) larger rear sprockets. However, engine mapping, fuel capacity, internal transmission gear ratios and its five speeds, and pretty much everything else in between, have been left alone compared to the Xs’ motocross counterparts. The Xs even come with the exact three black (Soft), green (Standard) and white (Hard) engine-mapping couplers as the motocrossers, but the Xs come from the factory with the least aggressive black couplers installed; the KX motocrossers, the Standard green couplers.
The Xs also borrow Kawasaki’s Launch Control Mode system from the KXs.
Like the KX motocrossers, the 250X is fitted with the same KYB suspension components as the KX250, and the 450X the same Showa suspension components as the KX450, but both are re-tuned for off-roading. Both forks (48mm for the 250X and 49mm for the 450X) use coil springs but are rated slightly softer than the motocross KX springs. The 450X’s fork, which features Showa’s A-Kit Technology, comes with a 4.8N/mm spring, and the shock a 52 N/mm spring; both fork and shock have updated valving. The shock still rides on the same linkage as the motocrosser.
The 250X’s KYB fork uses a softer 4.7N/mm spring but the same shock spring as the KX250 motocrosser. Damping front and rear have been re-tuned. The shock also rides on the same linkages as the KX250.
It’s worth mentioning that the Xs are not fitted with handguards, nor are they equipped with spark arrestors, and they are sold as closed-course race bikes. For Californians, this means they are considered “red-sticker” bikes.
Both Xs retail for $100 more than their motocross counterparts, but that’s a lot less than what you would have to pay to perform these same off-road mods to your KX motocrosser, and you don’t have the hassle.
2021 Kawasaki KX250X & KX450X Review | Happy Trails
We recently got our first chance to ride the new Xs. Kawasaki introduced both bikes to the media at the Cahuilla Creek MX track facility in Southern California, staking out a challenging five-mile off-road loop that included choppy single track, whoops, rocks, and the facility’s vet motocross track. The array of tight terrain and wide-open straights (top speeds of over 50 mph!) provided a challenging environment where we could get a good first feel of these new bikes.
Having already recently ridden both the 2021 KX250 and KX450, it was easy to feel the main difference between the KXs and the Xs—suspension! The Xs’ suspensions are noticeably softer and much better suited for the trail and even for high-speed off-road terrain than the KXs’ stiffer motocross suspension. On the wide variety of terrain and trails on which we rode (some of which were extremely tight), the X’s suspension hit the mark for us: not too soft, not too stiff, but just right. Kawasaki did an excellent job finding that sweet spot—compliant yet not mushy—with both bikes’ suspensions. We even found the X’s softer suspension to perform exceptionally well on the motocross track, at least for our admittedly “average” skill level. Pros will want to stiffen things up a bit, for sure, but for everyone else, we feel the X’s suspensions hit the nail on the head for aggressive riding and GNCC- and WORCS-type racing.
Going up a tooth on the rear sprocket on both bikes was the smart thing to do. This helped the 250 launch out of the turns a little quicker and put less stress on the clutch, and it also made it so you could ride the bike longer in second gear while keeping you out of first gear, which is now pretty much used just for emergencies. And if you’re really moving, it’s not unrealistic to hold third gear longer than usual, too. And we never found ourselves running out of revs when the trail opened up.
For off-roading, we tend to gear up 450s since they have the power to spare, but Kawasaki went in the opposite direction with the 450X. However, with the mellower black map, we found the combination made the 450X’s engine very manageable on the trail, and the extra tooth in the back also seemed to help prevent stalling when you come into a turn too hot and grab too much brake, or when creeping along over a technical section.
Although we wouldn’t say we abused the clutch on this day, we did put it to work at times, and, so far so good. We didn’t notice any fading, and clutch pull was light and remained consistent with good feel. This was the case with both bikes.
Like the motocross KXs, the Xs offer plenty of adjustments when it comes to ergos. The handlebars have a ton of adjustments, and the footpegs can be lowered. Both bikes feel narrow between your legs and very maneuverable on the trail. And the brakes are strong and have excellent feel.
The downside? Kawasaki forgot to install handguards at the factory and chose not to go with a higher-capacity fuel tank, which, with the Xs’ 1.64-gallon tank, could be an issue in a typical 40-plus-minute grand prix, or multi-hour-long races (aka GNCC and WORCS), or for extended trail rides with your buddies. But if Kawasaki had given the X a larger tank, we’d probably be complaining about how bulky it felt (compared to the KX MXers). This has always been a Catch-22 thing with the manufacturers. So, Kawasaki chose not to mess with it. Right or wrong? That’s up to you, really. But aftermarket tanks are already available for the Xs if you need more mileage.
But if a small gas tank and no handguards are all we have to complain about, we’d say that Kawasaki hit the mark with both these bikes.CN
2021 Kawasaki KX250X / KX450X Specifications
||$8399 / $9599
||4-stroke, liquid-cooled, DOHC, 4-valve, single
||249cc / 449cc
|Bore x Stroke:
||78.0 x 52.2mm / 96.0 x 62.1mm
||14.1:1 / 12.5:1
||DFI w/ Keihin 44mm throttle body & dual injectors
||Coned disc-spring, hydraulic
||27.8° / 27.6°
||48mm coil-spring KYB fully adj. fork / 49mm coil-spring Showa fully adj. fork
||Single KYB shock, Uni-Trak, fully adj. / Single Showa shock, Uni-Trak, fully adj.
||12.4 in. / 12.0 in.
||12.4 in. / 12.1 in.
||80/100-21 in., Dunlop AT81
||110/100-18 in, Dunlop AT81
||Single semi-floating 270mm Braking petal disc
||Single 240mm disc
||58.3 in. / 58.5 in.
||13.0 in. / 13.2 in.
||37.2 in. / 37.4 in.
|Weight (dry, claimed):
||230.2 lbs. / 235.8 lbs.
|Weight (curb, claimed):
||240.2 lbs. / 246.0 lbs.