How long can a stock PK125 keep up?

There's something about the max speed of my PK that's bothering me.
The user manual, and almost all data websites (motorcycles specs, and such) list the PK125's max speed as "90+km/h"

Okay, that's a very good speed for such a machine (no offense intended, but it is a city scooter from 30+ years ago). But my big question is:


How long can I keep this scooter around the max speed?

Will the engine seize after 5 minutes of 75km/h? Will it seize after 3 hours?

Is "slightly below max speed(70-75km/h)" a good "road traveling speed"?

Can I just ride my bike a whole afternoon without risking getting stranded in the middle of a country road?

I read so much about two-stroke engines, and heard so many opinions...

What's your opinion and/or experience on this?