I know that Kawasaki ninja 400 and KTM duke 390 are very different bikes, but this is what I have and I will provide some differences between the two. Actually the duke 390 is my wife’s motorcycle. So, the ninja is 2019 model, second hand, 12k km. The the Duke is 2019 model, brand new.
The ninja 400 have some analog displays. The duke is full digital. For me the ninja 400 have better looking displays. But the KTM is more useful. There is so much data in this display. For example I can have range, fuel consumption, rpm, speed, average trip speed, battery level and more at the same time! You also have setting when the RPM bar should change its color and when to blink.
The RPM display on the ninja is bad. I don’t know why kawasaki decided to have white rpm numbers and white arrow.
High beam change on the duke is done via the “flash” button. You can push it to the right and the high beam will turn on. To turn the high beam off you have to push the same button to the left. If you pull this button then the high beam will only flash. The ninja have the same button for the flash. But the high beam button is located above the turn signals. I found the KTM solution better.
The ninja seat height is much lower compared to the duke 390. I can put my both feet solid on the ground. On the KTM I’m stepping on my toes. I can’t decide if one is bad and the other is better. The ninja is more aerodynamic, but the KTM allow small off-road.
The KYM seat is so hard. It is like you are sitting on a wood bench. The ninja seat is the “soft version” and I found it too soft. I prefer harder ones, like the duke’s seat.
My Duke doesn’t have windshield. Speed over 90 kph feels like you are flying. I don’t have such issue with the ninja and 120+kph.
In my opinion the ninja accelerate faster. It also revs higher. ~10k redline for the duke vs 12k for the ninja.
Fuel tank of the ninja is wider. The duke have narrowed and taller fuel tank. I’m not sure which one is better.
Duke is the winner. No second options. You can see so much in the Duke’s mirrors.
The ninja have much more, like x3 times more storage capacity compared to the duke.
Starting the bile
The Duke is fully electronic. You need to press the button for 0.0001 seconds and the electronics will do the rest. The ninja require to hold the “start” button pressed until the bike starts. It need like a seconds.
The Duke looks better for first bike. It is also more comfortable for city driving. Anyway, ninja is my choice. If I have to pick again, the ninja will my choice again.