I had to painstakingly reach for my GD's owner's manual and share it here to clear the concepts for once and for all:


Now let's do the mathematics:
(1)- 3/4 of top-speed for GD with a theoretical top-speed of 120 km/h (as mentioned on its speedometer) = 120 * 3/4 = 90 km/h.
This is the maximum speed which "may" be reached during the break-in period, yet a slower speed is recommended in the break-in procedure.
(2)- Throttle opening should be restricted to 2/3rd of its limit during the initial 500 km at least. Let's take YBR's example. The maximum value on its tachometer is 12.
So, 2/3 of 12 = 12 * 2/3 = 8.
So the maximum safe RPM to which the YBR may be revved during break-in period = 8 x1000.
I hope it clears everything out. And let us not spread baseless concepts as our motorbikes are very dear to us and we don't want anything to go wrong with them at any stage.
Happy riding.