Although the super highway has Motorway status (so called M9) so legally bikes shouldn't be allowed there but I have seen bikes all over super highway, after the toll plaza, kathore more and even nooriabad so I guess it will be ok. However, Sindh Police might stop you for "chaye pani".
I have taken my 70cc bike till Keenjhar Lake and back three times on Old National Highway which is 125 km from Karachi. Never had any issue with engine overheating etc. Just took a small break at Dhabeji and Gharo for 10 minutes each.
Hyderabad is about 160 km via Super Highway so it should be a piece of cake for CG125.