2021 Kawasaki KX450 Review (First Ride Fast Facts)

For Ultimate Motorcycling‘s first ride of the 2021 Kawasaki KX450, I headed to the world-famous Glen Helen Raceway to put a few hours on the 2021 model. This bike was all-new in 2019, so 2021 is more of a fine-tuning year. This is a positive thing as Kawasaki has been refining a very popular and highly rated motocrosser.

2021’s key changes are in the clutch, suspension, and handlebars—we provided a full rundown of the 2021 KX450 updates earlier this month. Now it’s time to hit the track, one that has been used for AMA Nationals and MXGP racing.

2021 Kawasaki KX450 Review - Price

  1. The 2021 Kawasaki KX450 has an all-new clutch design for 2021. About the only criticism of the KX450 in recent years was towards the clutch. The KX450 now features what Kawasaki calls a coned disc-spring hydraulic clutch—basically a diaphragm-spring clutch rather than the traditional coil spring design. The idea is to improve the feel and durability. The new spring design makes for a lighter pull as the diaphragm is flattened out. We have all been there before where your clutch finger is worn out, your arm pumps, then you start using two fingers on the clutch and eventually need to stop and shake it off. I love to ride and want to be able to ride more hours without getting tired.

  1. The lighter clutch pull is noticeable and kept us riding aggressively longer with one finger on the clutch. The new hydraulically actuated clutch had a better feel and provided us with more ride time—a huge plus! The clutch also has better modulation and really made it easier to hold a line through a corner or any time you need to fan the clutch to stay in the right RPM range. If you have a 2019 or ’20 KX450, this clutch can be retrofitted to your bike. It won’t be cheap, but if you can afford it, do it. 

  1. The 2021 Kawasaki KX450’s Renthal Fatbar is an upgrade. Long overdue, the old 7/8-inch Renthal handlebar has been retired in favor of the 839-bend Renthal Fatbar. The bend is flatter and more swept back.

2021 Kawasaki KX450 Review - MSRP

  1. I spent a lot of time playing with bar placement, as I stand six-feet tall. The bar is highly adjustable, with four different positions—the stock position is the back-hole, forward clamp. I felt the bike needed more weight over the front, so I tested in the forward-hole location. It is better for fast standing corners, and gives me a little more room in the cockpit. However, it took a lot away from tighter cornering in the sitting position, so I eventually moved the bars back to the stock position with the bars rolled slightly forward. This provided the best all-around performance and comfort for my lanky frame. Overall, the new bend improves ergonomics, handling, and comfort—just take some time to set it up properly. The wide footpegs can be moved between two positions, though I was happy with the stock position. 

  1. The only engine mod is a minor, and not something we could feel. The piston skirt gets a dry film lubricant to help the motor rev quicker by reduction friction. It is not something I could feel, but the motor is still smooth and friendly. Don’t take that the wrong way and think I am suggesting it’s underpowered—it’s not. While I never struggled for power to climb Mt. St. Helens or to clear any of the jumps, the KX450 does lack excitement off the bottom. Instead, the power is linear, usable, and finds traction. It is arguably the best engine package in the 450 class to suit the broadest range of riders.

  1. Part of the motor’s appeal is its adjustability. Although not as complex or convenient as some systems, the KX450’s motor mapping options are important to touch on. The KX450 continues with three c plug-in coupler options to adjust mapping. The choices are Standard (Green), Hard (White) and Soft (Black). I started with the stock green coupler. After dialing in the chassis setup and getting comfortable with the green coupler, I plugged in the aggressive white coupler. The power increase is substantial, making it an excellent option for deep sandy tracks or expert+ level riders. For my style and Glen Helen’s track conditions, the standard option is best for me, and likely most riders.

2021 Kawasaki KX450 Review - Specs

  1. The KX450 also continues with launch control, a great feature to regulate engine output on the start straight to help prevent wheelspin. This was especially beneficial when we tested it out on the concrete starting gate. 

  1. I can’t praise the plush chassis and Showa suspension combination enough. With both featuring Showa’s high-end A-Kit technology, the stock suspension is so good that the majority of riders will have no need to send it out for expensive revalving work. Of course, if you’re outside the target weight, or you’re an AMA Pro, you may need to go stiffer. However, it was just right for me, as a 180-pound Intermediate Vet racer. The Kawasaki and Showa R&D departments have really done their homework and provided some of the best stock suspension I have tested. 

  1. The 2021 Kawasaki KX450’s fork is superb. Stock fork height is flush to the clamps, and that’s where I left it. I did soften the forks just a couple clicks, and made very minor adjustments to be completely comfortable on the rough and choppy Glen Helen track. The Showa fork, even if on the soft side, still holds up in the stoke good for me, and it helps me push through the rollers smoothly. It also handled the small bumps, particularly in corners, where it kept the tire planted and grabbing traction.

2021 Kawasaki KX450 Review - Photos 

  1. In stock form, the updated piggyback shock is perfect! I started at 106mm, as that’s how the bike was out of the box for my weight. It needed a little push forward in balance, and going to 104mm gave me the right feel. The shock felt good on the smooth, fast morning track, as well as the extremely rough late afternoon track. I anticipated having to make changes once the track got rough but left the shock at the stock settings. Featuring a new compression adjustment system and linkage ratios, the shock action is plush and doesn’t bottom-out through the huge breaking bumps on Glen Helen’s famous downhills. It also stayed planted through the acceleration bumps out of corners and up the hills. 

  1. Dunlop Geomax MX3S is Kawasaki’s choice for tires. I really like this tire, as it grabs the most traction and is more on the soft side of the soft/intermediate classification. The tire lacks durability on hardpack and requires slightly higher air pressure, but the traction is worth it.

2021 Kawasaki KX450 Review - Glen Helen Test

  1. The brakes are put to the test on the hilly Glen Helen circuit. When coming down the long Glen Helen hills, stopping power is extra essential. The front brake works as it should—nothing lacking or extraordinary. I do like that the KX450 comes with a larger 250mm rear rotor. Some feel this makes the rear brake a little grabby; if that’s the case for you, it can easily be fixed by installing the 240mm disc used on the KX250. I am a rear brake dragger, and tend to always have my foot hovering over the pedal. Even on a hot day on a track with plenty of elevation changes, I didn’t have any problems with the larger disc being too grabby or getting hot. 

  1. After spending the day on the 2021 Kawasaki KX450, it is apparent why it has been a Supercross championship motorcycle and arguably the best 450 on the market. The combination of a highly developed engine and suspension package with excellent ergonomics, plus outstanding traction, stability, and confidence. The 2021 KX450 was instantly comfortable for me to ride at my full potential!

Photography by Drew Ruiz


  • Helmet, pants, jersey + gloves: Thor Sector
  • Goggles: Thor Sniper Pro
  • Boots: Thor Radial

2021 Kawasaki KX450 Specs 


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


  • Frame: Aluminum perimeter
  • Handlebar: Renthal Fatbar
  • Front suspension; travel: Compression- and rebound-damping adjustable Showa 49mm inverted fork; 12.0 inches
  • Rear suspension; travel: Linkage-assisted fully adjustable Showa piggyback reservoir shock; 12.1 inches
  • Tires: Dunlop Geomax MX3S
  • Front tire: 80/100 x 21
  • Rear tire: 120/80 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


  • Wheelbase: 58.5 inches
  • Rake: 27.6 degrees
  • Trail: 4.8 inches
  • Seat height: 37.6 inches
  • Ground clearance: 13.4 inches
  • Fuel Capacity: 1.6 gallons
  • Curb weight: 243 pounds
  • Color: Lime Green

2021 Kawasaki KX450 Price: $9399 MSRP

2021 Kawasaki KX450 Review Photo Gallery