Kawasaki KX450 and KX250 Motocross Motorcycles

we see a consolidation of the chassis of the Kawasaki KX450 and KX250 motocross motorcycles. While the two motors are distinctive, the rest of the KX racers are more alike than dissimilar this year.

With that in mind, let’s talk about what is new for the KX450 (and the KX250), as well as the differences between the KX450 and KX250.

1. The KX line gets an all-new clutch design. Kawasaki completely rethinks its clutch by ditching the traditional five-spring design and going with a coned disk, which acts as a spring. Additionally, the clutch now has hydraulic actuation. Expect an increase in feel and a decrease in effort, especially in the second half of the lever sweep. Also, the clutch plates on the KX450 are a larger diameter with new friction material.

2. Renthal Fatbars come to the Kawasaki KX motocrossers. This is an upgrade over the old continuous-diameter aluminum bars of old, and the ergonomic of the KXes have changed. The grip position is now lower and closer to the rider. Of course, Kawasaki’s Ergo-Fit feature allows for extensive personalization. There are two mounting holes for the handlebar clamp, for 35mm of adjustability, and the clamps can be spun 180 degrees for two more position possibilities. Kawasaki also provides two footpeg mounts, 5mm apart.

3. Inside the motor, the piston skirt gets a dry film lubricant. This allows the engine to rev quicker, with less power loss thanks to reduced friction.

4. The 2021 Kawasaki KX250 gets serious motor mods, along with the move to the KX450 chassis. The top-end gets new ports, new cam timing for the exhaust (retarded three degrees), stiffer valve springs, plus a revised combustion chamber design with a flatter piston crown. In the bottom end, we see a 3mm-longer connecting rod, lighter crankshaft, improved pressure balance in the cases, plus the same all-new clutch used in the KX450. In addition to more power, the 2021 KX250 revs 300 rpm higher than last year.

5. We are all happy to see the 2021 KX250 get e-start. Yes, you can start the KX250 with the push of a button, thanks to a new starter (with an automatic compression release) and a lithium-ion battery. There is no kickstart backup.

6. The KX250 continues to have its own KYB suspension setup. Rather than mimicking the heavy and more-powerful KX450, the KX250 has its own suspension units. To keep the KX250’s cost down, the KX gets a standard KYB fork rather than the Showa A-Kit works-style technology used by the KX450.

7. Kawasaki put a 10mm smaller Braking rear disc on the KX250 than the KX450. The 240mm disc cuts a bit of weight and helps prevent rear-wheel lockup due to less engine compression braking.

8. To reduce interference with the rider’s boot, there are new engine covers. Kawasaki smoothed the covers down, and put a gold finish on the oil cap and generator cover plugs.

9. You can run down to your Kawasaki dealer right now and have a good chance of checking out the 2021 Kawasaki KX450 and KX250. The KX450 hits the showroom floor with an MSRP of $8999, while the KX250 has a tag of $6999.

2021 Kawasaki KX450 (and KX250) Specs

ENGINE

• Type: Single-cylinder four-stroke
• Displacement: 449cc (KX250: 249cc)
• Bore x stroke: 96.0 x 62.1mm (KX250: 78.0 x 52.2mm)
• Compression ratio: 12.5:1 (KX250: 14.1:1)
• Starting: Electric
• Fueling: EFI w/ 44mm Keihin throttle body (KX250: dual injectors)
• Transmission: 5-speed
• Clutch: Hydraulically actuated w/ coned-disc spring
• Final drive: Chain

CHASSIS

• Frame: Aluminum perimeter
• Handlebar: Renthal Fatbar
• Front suspension; travel: Compression- and rebound-damping adjustable Showa 49mm inverted fork; 12.0 inches (KX250: Compression- and rebound-damping adjustable KYB 48mm inverted fork; 12.4 inches)
• Rear suspension; travel: Linkage-assisted fully adjustable Showa piggyback reservoir shock; 12.1 inches (KX250: Linkage-assisted fully adjustable KYB piggyback reservoir shock; 12.4 inches)
• Tires: Dunlop Geomax MX3S
• Front tire: 80/100 x 21
• Rear tire: 120/80 x 19 (KX250: 100/90 x 19)
• Front brake: 270mm Braking semi-floating petal disc w/ dual-piston Nissin caliper
• Rear brake: 250mm Braking petal disc w/ single-piston Nissin caliper (KX250: 240mm disc)

DIMENSIONS and CAPACITIES

• Wheelbase: 58.5 inches
• Rake: 27.6° (KX250: 28.0 degrees)
• Trail: 4.8 inches (KX250: 4.6 inches)
• Seat height: 37.6 inches (KX250: 37.4 inches)
• Ground clearance: 13.4 inches (KX250: 13.2 inches)
• Fuel Capacity: 1.6 gallons
• Curb weight: 243 pounds (KX250: 237 pounds)
• Color: Lime Green

2021 Kawasaki KX450 Photo Gallery

Kawasaki KX250 Photo Gallery