With regarding xvs 125 give a little more poke
When I was 16 on my first moped that would also do 70- 75 on a good day
My 125 would do about 110ish
You will be able to find out whether it's restricted by final drive sprockets carb inlet size main jets needle height Exhaust But you must do everything not just one as doing just 1 will make the bike run lean then seize or blow up...
If you have the money then get a big bore kit
lol maybe you should pop down your local tire garage and ask them to use an air wrench or a 6ft bar on the end and lightly tap the socket with a hammer to crack the seal