Putting the number aside for a moment, think of it like this: if it's working, you should be able to wind it out to maximum revs at maximum gear, and run out of gear ratio and revving capability, before you run out of power to get there. As standard, almost every bike or scooter is able to redline in top gear. You should be able to hit that, regardless of the numbers on the speedo. If not, then you have problems.
As for the number, yes, it should sit at (actual) 70 comfortably, 85 is a stretch. You can probably bring 90 up on the dial but it's unsustainable as a cruising speed.