Harley-Davidson Fat Boy vs Yamaha Sirius FI

The Harley-Davidson Fat Boy (2025) and the Yamaha Sirius FI (2025) 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 Harley-Davidson Fat Boy is a cruiser with 1,923 cc, 103.3 hp and 315 kg; the Yamaha Sirius FI is a cub / underbone with 114 cc, 8.6 hp and 98 kg. Power-to-weight with the rider: 264.8 hp/ton versus 49.6 hp/ton. On this measure the Harley-Davidson Fat Boy is 434% ahead.

0-100 km/h (speedometer): Harley-Davidson Fat Boy 3.54 s, Yamaha Sirius FI not reached (top simulated speed 89 km/h). In the 60-0 km/h brake test, braking distance without the 0.3 s reaction time is 17.7 m for the Harley-Davidson Fat Boy (ABS unknown, class assumption: no ABS) and 18.5 m for the Yamaha Sirius FI (ABS unknown, class assumption: no ABS). The Harley-Davidson Fat Boy stops 0.8 m shorter. The standard 60-0 test is used because one calculated top speed is below 110 km/h. Calculated top speed: 201 km/h (estimated from power and drag) versus 88 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 class-average calibration (no accepted model-specific road test) for both. Open the interactive app (currently in Turkish) to watch the run side by side and change the load.