2021 Kawasaki KX450X

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Bike Test: 2021 Kawasaki KX450X

Tester:Chris Siebenhaar
Age: 35
Height: 5’ 10”
Weight: 178 lb
Class: Intermediate/Expert

2021 Kawasaki KX450X

The power plant is identical to the KX450 (mx model). It does come stock with the black (mellower) coupler in the bike, but also has green (middle) and white (aggressive) couplers.

18 inch rear wheel.
One tooth was added to the rear sprocket (51).
A small glide plate is included.

This year the off-road (racer) category just got a little deeper with the addition of Kawasaki throwing its hat into both the 450cc, and 250cc cross country ring. Both bikes got the same off-road treatment, meaning softer suspension, a kickstand, skid plate, different final gearing, and 18” rear wheel and Dunlop AT81 tires. Other than that they’re basically the same as their motocross brethren. But is that good enough?

As mentioned above, the changes made from the 450 MX version are minimal, but a necessary starting point to move in the right direction. Having just come off the 2021 450 MX Shootout and having raced a 2020 KX450 (MX Spec) off-road last year, I have a very good understanding of the bike’s traits and how it performs in an off-road racing environment. First thing to mention (that has been pointed out numerous times) is that there are certain things this bike lacks when compared to some of the other machines. When compared to other Japanese bikes it lacks an oversized gas tank. Compared to the Austrian bikes it lacks the gas tank and handguards. But are those deal breakers? No. Having raced multiple off-road race series (WORCS, Big6, Hare ‘n Hound), the fact is most classes are in the 45-60min time bracket, typically only the pro-classes are 1.5 hrs or more. That being said, a stock gas tank is more than adequate to run in most hour-long races (wide-open/fast courses may be different), having an oversized tank is just carrying more weight. Handguards are a personal preference, I typically would only run them on a course that goes through trees or thick bushes, but not an open course.

But other than the small details, was Kawasaki being lazy with just slightly modifying their motocross bike? In my opinion, no. In the 450 MX shootout the KX450 was my number one pick for two reasons, the motor and the suspension. Personally, I think the motor is a fantastic power plant. It has great torque, a very liner power delivery with excellent mid and top end, and while it’s plenty fast, it’s also very manageable which is important in the latter stages of hour long races. Because of this, I think it’s a very versatile engine that is at home both on tracks and trails. I loved the suspension of the MX bike for one main reason; control. The bike had a very smooth movement in terms of pitching (diving under braking and squatting under acceleration), this is important as excessive pitching will cause a bike to standup or pop out of ruts. For the 450X, Kawasaki (and SHOWA) kept this feeling of control and added just a bit more comfort by softening up both ends. While the suspension was still a little firm for slow speed rock sections, it was excellent through fast rollers, sandy switchbacks, and the occasional free ride jumps. On both the GP track (fast, rough, no jumps) and the vet track the suspension held up very well. This is the area where some of the cross-country racers tend to lack, some favor the slower speed sections with plush suspension but then sacrifice greatly on the track with suspension that dives, pitches and bottoms when pushing ever so slightly. 


Both these “X” models are a great starting point for Kawasaki, and with the addition of them getting into the cross-country segment only means one thing, the category is growing and this is great news for the off-road community. With more models, usually comes better racing, more contingency, and a better spread of competition. As for the bikes themselves, they will perform good-to-great for most riders. While there will certainly be some off-road-focused riders will opt for adding items to suit their own needs (hand-guards, burley skid plate, oversized tank, etc), off the showroom floor you will be given a good foundation. 




Product Kawasaki KX450X
Model Year 2021
Engine Size 450cc
Engine Type Four-Stroke
Engine Displacement 449cc
Bore x Stroke 96.0 x 62.1mm
Compression Ratio 12.5:1
Fuel System DFI® with 44mm Keihin throttle body
Ignition Digital CDI with 3 Coupler Options
Transmission 5-speed, return shift, with wet multi-disc manual clutch and hydraulic clutch actuation
Final Drive 13-51 Chain
Suspension Front 49mm inverted telescopic coil-spring fork with 16-way compression damping and 16-way rebound damping/12.0 in
Suspension Rear Uni-Trak® gas charged shock with piggyback reservoir with dual-range (4 turns stepless high speed/19-way low-speed) compression damping, 22-way rebound damping and adjustable preload/12.1 in
Brakes Front Single semi-floating 270mm Braking® petal disc with dual-piston caliper
Brakes Rear Single 240mm Braking® petal disc with single-piston caliper
Tires Front 80/100-21
Tires Rear 120/80-18
Overall Length 86.0 in
Overall Width 32.3 in
Overall Height 49.8 in
Seat Height 37.4 in
Wheelbase 58.5 in
Ground Clearance 13.2 in
Rake/Trail 27.6°/4.7 in
Fuel Capacity 1.64 gal
Curb Weight 235.8 lb without fuel / 246.0 lb**
Price $9,599
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