The Kawasaki KX450 received what we call a “ground-up rebuild” for the 2019 model year. They addressed almost every issue we had with the machine in previous years, and it has won the last two Dirt Bike magazine 450cc motocross shootouts. Factory racer Eli Tomac has been very successful aboard the machine as well, winning multiple professional championships. For 2021, Kawasaki made a few changes that are more like refinements of the already-proven platform. We can’t say that we blame the Kawasaki engineers for being reluctant to make major changes. If it’s working, why change it?
The list of new features for 2021 is short, but that is not necessarily a bad thing. Kawasaki has been the lone standout manufacturer using 7/8-inch-diameter handlebars, and for the first time in history, the KX450 will come with Renthal Fatbars as standard equipment. Another change for 2021 is the addition of a dry-film lubrication coating on the piston skirt. This coating is supposed to reduce friction between the piston and cylinder wall for better durability and increasing overall engine performance. The last new item on board for 2021 is also inside the engine—this time in the transmission, and frankly not something that was on our radar as a bad thing. The coil-spring clutch has been replaced with what Kawasaki is calling a coned disk spring, which is similar in design to the version used by KTM that they call the DDS clutch. Kawasaki is trying to achieve a lighter clutch pull and a wider clutch-engagement range to help improve control. This system uses large-diameter clutch plates, and different friction-plate material is designed to provide a consistent feeling while reducing fade during heavy use. The friction plates also have new offset segments to reduce overall drag.
The chassis returns unchanged for 2021 using an aluminum perimeter frame that features forged, extruded and cast parts, while using the engine itself as a stressed member, adding to the frame’s rigidity balance. The swingarm is constructed of a cast front section and twin-tapered hydro-formed spars with pivot points that focus on the center of gravity for balanced handling. Once again, Kawasaki uses Showa suspension components on the KX450 with 49mm coil-spring fork with A-kit technology and DLC-coated tubes up front while utilizing their Uni-Trak linkage system and a Showa shock also featuring A-kit technology just like the fork. Braking components are still Nissin, with a 270mm petal-shaped Braking rotor up front and a 250mm (largest in the class) version from Braking in the rear.
Adjustability, just like on the previous years, is a big part of the 2021 KX450, with adjustable handlebar mounting positions offering two mounting holes with 35mm of adjustability, and the 180-degree offset clamps giving the rider four different mounting points to choose from. There are also two different footpeg mounting positions—stock and 5mm lower—to suit different-sized riders. Graphics are still molded into the plastics, but have been ever so slightly updated for 2021, but no major styling changes were made using the same plastics that were introduced back in 2019.
Since its redesign in 2019, the Kawasaki KX450 has received a warm reception from the public with increased unit sales and in the media with positive reviews. It has won the Dirt Bike magazine 450cc motocross shootout since its introduction, and the few changes made for 2021 don’t hurt the KX450 chances for another shootout victory.
We didn’t have any major issues with the clutch in previous years, so the 2021 version using a cupped disc spring instead of coil springs was a bit of a surprise. Although this is new to Kawasaki, we have seen this type of design concept from KTM/Husqvarna in the past. The new clutch pull is light, just like in previous years, and for most people this is great news, but some people find themselves over using the clutch, and that can prematurely wear the plates. That being said, our 2020 test machine has seen a lot of action this year without having any major issue in that department. The 2021 version locks in harder, almost eliminating the vagueness of last year’s model.
We did have some issues with our 2020 model sub-frame—the rear muffler mount breaks along the weld. This happens with intermediate- and pro-level riders, especially when using an aftermarket exhaust that is not rubber-mounted like the stock unit. Although we did experience the same issue with rubber-mounted units, it just took a little longer to happen. We haven’t had this issue on the 2021 model yet, but without Kawasaki making any changes to this area, it seems to be only a matter of time.
Handling and power are still excellent. The Kawasaki was already the lightest of the Japanese 450s. On our scale, the 2021 model weighs 235 pounds without fuel. With a ride-height setting between 103–105mm, it still has a more stable, well-planted feel than virtually any other 450. That’s what we loved about the 2019/2020 version and why it won our last two 450 shootouts. It isn’t the fastest bike in the class. It’s actually one of the slowest, according to the dyno. But, you don’t walk away thinking about it in those terms. It’s super smooth and easy to ride. It revs out cleanly without a sudden rev-limiter shutdown. Kawasaki has done a good job setting this bike up for the masses by giving it adjustability, rideability and durability all without being the standout leader in any one category.
2021 KAWASAKI KX450
Engine type: Electric-start, four-valve, DOHC, four-stroke
Bore & stroke: 96.0mm x 62.1mm
Fuel delivery: 44mm Keihin EFI
Fuel tank capacity: 1.6 gal.
Lighting coil: No
Spark arrestor: No
EPA legal: No
Weight, no fuel\: 235 lb.
Ground clearance: 13.4”
Seat height: 37.4”
Front tire: Dunlop MX33S 80/100-21
Rear tire: Dunlop MX33S 120/80-19
Fork: Showa 49mm, adj. rebound, comp./12.0”
Shock: Showa, piggyback, adj. preload, comp., rebound/12.0”
Country of origin: Japan
• Easy to use power
• Improved hydraulic clutch
• Side-access airbox
• Electric start
• Strong brakes
• Larger-diameter handlebars
• Lightest Japanese 450
• Weak sub-frame rear pipe mount
• No on-the-fly map switch
• Difficult preload- adjustment access