Kawasaki Z900 vs RKS RZ125

The Kawasaki Z900 (2025) and the RKS RZ125 (2026) are compared with the same Moto Kıyas physics model under identical conditions: flat dry asphalt, no wind, a 75 kg rider and no passenger. The Kawasaki Z900 is a naked bike with 948 cc, 122.0 hp and 213 kg; the RKS RZ125 is a sport bike with 125 cc, 14.5 hp and unlisted weight. Power-to-weight with the rider: 423.7 hp/ton versus 63.8 hp/ton. On this measure the Kawasaki Z900 is 564% ahead.

In the simulation the Kawasaki Z900 covers 0-100 km/h (speedometer) in 3.13 s and the RKS RZ125 in 13.42 s; the Kawasaki Z900 is quicker by 10.28 s. In the 100-0 km/h brake test, braking distance without the 0.3 s reaction time is 43.7 m for the Kawasaki Z900 (with ABS) and 36.4 m for the RKS RZ125 (with ABS). The RKS RZ125 stops 7.3 m shorter. Calculated top speed: 234 km/h (manufacturer claim) versus 125 km/h (estimated from power and drag).

All values are an estimated simulation, not road-test measurements. Technical data comes from the sources listed below; the model uses model-specific parameters calibrated against published road tests for the Kawasaki Z900 and class-average calibration (no accepted model-specific road test) for the RKS RZ125. Open the interactive app (currently in Turkish) to watch the run side by side and change the load.