A bullet-point history of the Kawasaki KX250 would miss all the really important facts about the bike. Yes, it would point out that it’s the winningest bike in the modern era of pro motocross; the KX250 (formerly known as the KX250F) has earned 18 championships and 189 wins in pro motocross and Supercross. That’s just a matter of records. It would certainly point out 2004 as the first year, 2006 as a complete redesign and 2011 as the arrival of fuel injection—all footnotes to the real story. The most relevant take-home fact about the KX250 is that most years it has been the easiest bike to race, the most fun to ride and the least expensive to own.
The bullet-point entry for 2021 would probably be the most misleading of all: “Electric start arrives.” In truth, that’s one of the least important facts about the bike. The 2021 Kawasaki KX250 opens an entirely new chapter in the legacy of one of the most successful race bikes of the current era.
THE KX CHRONICLES
As far as the bullet points go, the Kawasaki KX250’s pro-level success is thanks mostly to the efforts of the Monster Energy Pro Circuit team. The bike’s history started in 2004 in a weird, half-forgotten alliance between Kawasaki and Suzuki. The first KX250Fs and Suzuki RM-Z250s were built on the same platform, much like the KTM/Husky/GasGas products of today. Unlike with the KTM arrangement, there was no joint ownership between Kawasaki and Suzuki, only the desire to share development costs and go after Honda and Yamaha. Even though the arrangement looked good to company brass, it didn’t work out, because the ground troops on both sides didn’t like the idea of giving away their secrets. For 2006, a Kawasaki-only KX250 was developed, with Suzuki following suit with its own RM-Z250 by 2007.
- Excellent peak power
- Broader powerband
- Hydraulic clutch
- Electric start
- Adjustable ergonomics
- Excellent suspension
- So-so low-end power
- Busy handling
- Hard grips
The 2021 KX is every bit as groundbreaking as the bikes in 2004 and 2006, but salesmen will doubtlessly concentrate on electric start as the key selling point. Okay, we like electric start, too, but this is a whole new bike that evolved in three distinct phases. The 2019 Kawasaki KX450 was the first version of this model, getting a new chassis and motor with electric start. In 2020, we expected the KX250 to follow with the same treatment, but that didn’t happen. The 250 needed more work, so the redesign took place over a two-year period. The priority of 2020 was to increase peak power. That was accomplished through a remake of the valve train, using finger-followers between the cams and the valves, among other things. Finger-followers are little levers that increase the mechanical advantage on the valves, and they’ve proven to be very effective on KTMs and Hondas.
Kawasaki finished the job this year. The new KX250 got a 3mm-longer rod (no change to stroke). Even the top end was further developed. It now benefits from a new port-finishing process, new cam timing, a beefier cam chain and thicker cam-chain gears. The piston is new, as well as the shape of the combustion chamber. The rev ceiling was increased 350 rpm and now tops out at 14,500. Then Kawasaki moved on to the bottom end. The electric start is located behind the cylinder, and the clutch is completely redesigned. The coil springs are gone, replaced by what Kawasaki calls a coned-disc spring. This is essentially the same idea that KTM calls a diaphragm spring and the Maico guys called Belleville springs. Outwardly, the most obvious change to the clutch is hydraulic actuation. It now has a Nissin master cylinder on the left side of the bar and a slave cylinder on the left side of the motor.
The chassis is the same as the 450’s, aside from motor mounts, suspension and a smaller rear brake rotor (240mm versus 250mm on the 450). The KX250 uses KYB suspension instead of Showa, which is done to keep competing providers in the mix. The 250’s fork isn’t as trick-looking as the 450’s, mostly because it doesn’t have the dark Ti-nitride coating on the fork tubes. In terms of quality and expense, the KYB fork is similar. It uses coil springs and a 25mm piston with a Kashima coating on the outer tubes to reduce friction. In the rear, the KYB shock body also uses a Kashima coating.
The first thing you need to know about the 2021 Kawasaki KX250 is that it’s fast. That shouldn’t be a surprise; it already was fast. The 2020 model, with its redesigned top end, was actually the dyno king in last year’s 250 MX shootout by the tiniest margin. The problem was that it only carried its peak power for a blink of an eye. It didn’t have anything else, below or above. That came as a disappointment to those who loved the previous iteration, which was the torque king. The 2019 Kawasaki KX250 was the easiest 250 of the year to ride, whereas the 2020 was one of the most difficult. Now, the 2021 version will land somewhere between those two extremes. It makes as much peak power as ever, but now it carries that peak much further. It starts sooner and ends later, making the rider’s job much easier. It might still be the horsepower king as far as the peak number is concerned—only now, that will be less of an empty crown.
If you think you’re going to short-shift the bike and torque it around the track like the KXs of old, you might have to adjust your way of thinking. Those days are gone. One by one, each of the top 250 four-stroke motocross bike makers has come to the realization that low-end power isn’t the way to win. First, KTM and Husky came out with high-revving motors that blew all the others away. Then Honda did it, and one by one all of the current 250 four-strokes switched to the scream-it-like-you-mean-it way of thinking. How difficult is it to keep the new KX250 on the bubble? That’s where the new Kawasaki really shows improvement. The motor is super responsive. If you get caught in the low-rpm no-man’s land, you don’t have to stay there. It will climb out on its own if you’re willing to wait a millisecond or two, or you can use the clutch to bring it around. The new hydraulic clutch is extremely easy to use. One finger is all it takes to bring the revs up and get you moving. The pull is so easy that you might start using it as a crutch. It takes a little discipline to make sure you’re in the right gear to start with rather than coming in sloppy and trying to make up the difference with your left hand. Previous Kawasaki KX250s have always had an easy clutch pull, but very few serious racers actually raced them like that. The clutch needed heavier springs in order to last more than a race or two. So far so good with this version. After 10 hours, the clutch was as strong as in hour one.
If you want to modify the power delivery, Kawasaki offers you options, but they aren’t as advanced as those of some other makers. There’s no smartphone app, just three electronic couplers that allow you to choose between limited options. The white coupler makes the bike hit a little harder; the black one makes it softer. We’re not talking big differences here. Most riders like the standard or white couplers. They both make the bike a little raspy-sounding with popping on decel. The black coupler takes away a little responsiveness without giving much in return. If you really want to experiment, Kawasaki offers a calibration tool that allows you to make more substantial changes. It’s a little pricey, though—$700 for something that Yamaha gives you for free.
In one respect, this 2021 KX250 is just like everyone before it. It’s a great-handling bike that’s fun to ride. The KX strikes a magic balance between agility and stability that makes going fast easy. It can get busy, but that’s probably what makes the bike a blast; things are always happening, but nothing gets out of hand. In the past, we always figured this was because the bike enjoyed the happy combination of having not too much power and not too much weight. Neither of those things is true anymore. Now, it’s very fast and somewhat heavy. With the coming of electric start and the hydraulic clutch, the bike gained weight, as expected. On our scale, the 2021 model weighs 228.7 pounds without fuel, which is 5 pounds more than last year. The 2020 Honda and Yamaha were 227 pounds each, while the Husky and KTM were 219 and 218 pounds, respectively. The Suzuki was 227. At this point, we are going to say that the weight is just a number. There’s nothing about the new KX that feels porky or clumsy. On the contrary, it’s easy to toss around. It still turns as well as ever, and high-speed stability is excellent.
Give some of the credit to the suspension. Any 250 is going to be a challenge for base settings from the manufacturer. In this class, more than any other, you have a wide range of customers, ranging from the 120-pound mini-bike graduate to 200-pound vets. The best you can hope for is a well-balanced package that lands somewhere in the middle. Kawasaki did that well. For 165-pound intermediates, the bike is about perfect. We liked it best with 105mm of race sag and slight increases in compression damping. The fork holds up well in hard cornering, but as we said, it’s a busy bike. The fork and shock are always moving, sometimes a little too much. You can combat this with more clicks in every direction, but at the same time, you don’t want to go too far and ruin the plush ride. No matter what, the KX is still predictable and generally sucks up hard, unexpected bumps well.
BITS AND PIECES
You can tell that someone at Kawasaki got tired of hearing that KXs are a little lacking when it comes to details. That issue is being addressed; although, it won’t be an overnight change. The bike still has abrasive little grips, thin levers and a loud exhaust note, but at the same time, there’s progress. The handlebar is a Renthal Fatbar—no more 7/8-inch throwbacks to the ’80s. The seat foam is holding up so far. The plastic doesn’t get those little white impact craters after the first ride, and the bike still has a crisp, tight feel. It’s still the only major motocross machine with adjustable-height footpegs. This really is a significant step forward for Kawasaki. Is it a return to the days of real-world friendliness and grass-roots value? It’s certainly a move in that direction. But, more than anything else, the 2021 Kawasaki KX250 is the start of a whole new era when pros and amateurs will benefit from the same things.
2021 KAWASAKI KX250
- Engine type: Electric-start, four-valve DOHC four-stroke
- Displacement :249cc
- Bore & stroke: 78.0mm x 52.2mm
- Fuel delivery: 44mm Keihin EFI
- Fuel tank capacity: 1.6 gal.
- Transmission: 5-speed
- Lighting coil: No
- Spark arrestor: No
- EPA legal: No
- Weight, no fuel :228 lb.
- Wheelbase: 58.5”
- Ground clearance: 13.2”
- Seat height :37.4”
- Front tire: Dunlop MX3S 80/100-21
- Rear tire: Dunlop MX3S 100/90-19
- Front suspension: KYB 49mm, adj. rebound, comp./12.4” travel
- Rear suspension: KYB, piggyback, adj. preload, comp., rebound/12.4” travel
- Country of origin: Japan
- Price: $8299