Rechecked the numbers:I don't remember exactly what the top speed worked out to be, but it was somewhere in the range of 180-190 km/h (112-118 mph) in 6th at redline.
Primary Drive Ratio = 71/23 (~3.09)
6th Gear Ratio = 24/28 (~0.86)
Final Drive Ratio = 42/14 (~3)
Redline = 13500 RPM
Rear Wheel Circumference = 1.972 meters (taken from https://www.tacomaworld.com/tirecalc?tires=140-70r17)
Now for the math:
13500 * 3.09 * 0.86 * 3 = 1700 wheel RPM
1700 * 1.972 = 3354 m/min
60 min / 1 hr and 1 km / 1000m, therefore
3354 * 60 / 1000 = 201.2 km/h, or 125 mph
A bike with stock gearing and tire size cannot exceed 200 km/hr (125 mph) without exceeding the redline.
Please feel free to check the math, I will then consider it 'peer reviewed'
I cannot say for sure whether to expect this as a reasonable max for the average rider, seeing as you are likely to run out of steam before reaching it (again, on a stock bike). The data posted by @vulgr shows that skilled folk are able to really squeeze every last little bit of juice out of the little Ninja, which I consider a testament to their skills. They are really riding to the limits of this machine.