Alot of times the clutch will be hard to pull if the cables old. Have you tryed a new clutch cable? If the cables not the issue, try a new perch and lever
first lube the cable, dont use chain lube. Buy cable lube. If that doesnt work check for any binding along the cable. Still doesnt work check the clutch basket, if it has grooves in it then that is your problem, if it doesnt have grooves then replace the cable