non-nylon coated clutch cable can be oiled, sounds like a badly dragging clutch, ignore the manual on this one and adjust up the clutch free play more to see if that frees the plates but not so much that you get clutch slip, if not check the plates for distortion and wear in the clutch basket grooves, not sure if this bike has a push rod in the clutch, this may be worn/damaged therefore not giving the correct lift.
Ted, September 2011