2019 - 2025 KX450 Review and Modification

Bran New with 'Magic' graphics.

Quick Summary - The 2019 KX450 is a great compromise of engine response / power, compliant frame, and quality suspension components.
The engine power is very good, but first 1/8 turn throttle response ‚Äčis slightly aggressive in ruts. (This is easily fixed with Too Tech ECU re-mapping) The bike turns well and is a good compromise between initial turn in and straight line stability. The compliant nature of the frame enhances straight line stability and rider comfort, but probably detracts from ultimate front end turn in precision. The suspension is claimed to be soft in the front by many, but Too Tech testing illustrates that an overly stiff rear suspension causes the front end to move up and down excessively confusing the feel as too soft. Too Tech Suspension re-valving and ECU re-mapping improves the KX for a wide range of weekend racers and less aggressive off road.

The bike is a nice balance of front end grip with rear steer character. The frame is soft and compliant which helps the suspension absorb square edge bumps but probably negatively affects ultimate front end precision. The front traction does not match a Honda or KTM turn in, but straight line stability is clearly better than a Honda. Again a nice compromise!

Rough Tracks
Any bike works well on a nicely groomed track!!
It takes good suspension components AND a compliant (flexible) frame to work well in the rough. The forks can not respond quickly enough to sharp edges by themselves. Frame flex must assist the forks to absorb the high speed sharp edge bumps. The KX450 frame is clearly assisting the forks in making the KX a pleassure to ride. After the first few hours of riding (the honeymoon period) In stock form MOST riders notice the suspension doesn't respond with enough compliance in the rough square edges. This causes the bike to dance around in the rough and not settle into rough turns or track well out of the turns. It also makes it harder to roll on the throttle as the bike is busy in the bumps. Once the overall damping circuits are adjusted for the mortal riders at the throttle, the stock KX450 becomes much more fun to ride and a better bike in a wider variety of terrain.

Suspension Components
The 49mm Showa forks are essentially identical to the Honda CRF450R forks. They share the same internals but are coated internally and on the outer tubes for less friction and improved wear. These forks are previous A Kit quality.
The shock is also almost identical to the CRF450 unit. It does have a different design Compression adjuster but both adjusters can be modified to duplicate each other. Basically top notch components!

The power is deceiving. While not offering as much top end HP as the Honda, the low RPM torque is greater making the bike easy to control and hook up out of slippery turns or rough terrain. The 3 different maps allow the rider to experiment with different power deliveries.
Too Tech is using the KX FI ECU Calibration tool to create better throttle control in rough or sensative throttle applications (ruts, square edge exits) while also delivering noticeably MORE power at part to full throttle openings!! Over rev is significantly improved. (Although not quite Honda top end power, the improved control at low throttle openings and improved top end power put the KX on par with all of the 450's).

This is a great all around bike. It is narrow and light allowing lighter smaller riders to ride well on it while larger folks can adjust the handlebars and footpegs to suite their needs. The frame absorbs the sharpest edges, the hydraulic clutch eases lever pull and ensures a consistent engagement point, the engine offers a great power delivery compromise and it has electric start while being the lightest Japanese bike by far.
Nice Job Kawasaki.