Well leave the idea if you love your bikes and yourlives, You can travel from Khi till Bela (250km), till Bela is what i consider to be safe, After Bela comes Wadh, one the most notorious gangs of Balochistan, these gangs are filthy rich and can chase you on even 4x4. So i wont recommend you guys touring from Karachi to Quetta on RCD highway.
If you really want to visit Quetta with bikes. Book them on Coaches and enjoy the lovely ride in Quetta. @r1 has best highlighted the red zone areas. I would never dare to cross Khuzdar on bike being a punjabi :D