Ask the owner before you if it has a racing clutch installed.They clamp hard so the clutch will not slip but require force by your foot to unclamp.If the car has other tuner junk like a loud muffler it may have a racing clutch.A lightened flywheel and a racing clutch is a natural pairing but put stress on the crank bearings so your motor may be trashed already.Replace all of it fast and that fartcan muffler as well.An over tightened adjustment nut could make it stiff but if it is like a weight machine then you have a racing clutch.