2019 KX450 Review and Modification

Bran New with 'Magic' graphics.


IN SHORT, THE 2019 KX450 IS AMAZING
The raw truth: I like to ride all of the new bikes to form my own opinion about how they work and what they will need for suspension changes. As I got onto the bike I was thinking how lucky I am to ride Hondas with their lower seat height.
After 2 laps I was so impressed with its neutral handling, the ability to ride wide or tight lines and change my direction mid turn, AND MOST IMPORTANT - how the frame was assisting the forks absorb the chop without jerking the bars left and right.
I rode it another 10ish minutes and realized it was as good as I thought it was!
Handling
It works in a tight turn, up on the berm, or anywhere inbetween. I find I can enter a turn and change my exit point mid turn if desired. Initially I struggled in the ruts. Subsequently I pulled up the forks to the second line, changed the internal spring preload to the upper groove, and lowered the rear shock internally to lower the bike about 5mm. The slightly lower stance improved my rut riding without any detriments to overall handling.
I have seen other reports of the bike being too soft. After riding the bike and making valving changes for several riders, my conclusion is that only the most aggressive riders under 200 pounds will need stiffer springs! Most lighter Vet riders will appreciate lighter springs......
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 almost 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!
Engine
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.
We have been experimenting with custom ECU mapping using the KX FI Calibration tool. The tool allows better control in rough or sensative throttle applications while delivering MORE power at mid to full throttle openings!! (Although not quite Honda top end power, the improved control at low throttle openings more than makes up for it).
Conclusion 
So far 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