2019 - 2020 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.

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 turn in, but straight line stability is clearly better than a Honda. Again a nice compromise!
Initially I struggled in the ruts and sharp turn in. After realizing that the front and rear tire had more than 10mm clearance to the fender, I lowered the front and rear 6+ mm internally. The lowered stance improved my rut riding and ability to cross lines and square up turns without any detriments to overall handling.

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. Once the valving is properly adjusted for the riders speed and weight, the stock KX450 becomes an even better bike than stock.

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 past 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 mid 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.