Ninja 400 owner here at 800+ miles, honestly keep at 8 to 10k rpm max and as long as you usually keep it at 6 to 7k you'll be fine. Look up Fortnine's break in vid on YouTube literally talks about how riding a bike without any stress is kinda bad too. Don't ride it like you stole it, but don't be afraid to open it up either. But the RPM limit would probably have to be lowered due to higher stress that the stroked engine would experience. For example the 58.6 mm stroked motor at 11,700 RPM would have piston travel (in feet per minute) of 4500 FPM vs the 400's 13240 RPM to reach the same 4500 FPM with the standard 51.8 mm stroke. EURO 5 Ninja 400. BS6 Ninja 300. Locators . Dealer. Guidelines for Customer. Dealer Locator 50.2 kW {68 PS} / 8,000 rpm: Maximum power with Ram Air-Maximum torque The engine redlines at a massive 16,000 rpm, while the peak torque rating of 36 Nm is 1 Nm lower than the Ninja 400. The engine is mated to a 6-speed gearbox with Kawasaki Quick Shifter (KQS). NINJA ® 400 KRT EDITION. MSRP $ 5,499. SELECT MODEL. 2023. NINJA ® 400 KRT EDITION ABS. MSRP $ 5,899. SELECT MODEL. Subtotal ( 0 Item) Sporty, but not uncomfortable, light, yet with enough punch even in the lower gears. A friend of mine owns the 2020 Ninja 650 and that bike is a bit bigger and heavier, not as nimble. The seating position is also a bit sportier on the Ninja 400 and the seat is stiffer. But what I personally really like about the 400 in comparison with the 650 D6zSt.

ninja 400 rpm limit