It's time to get really serious. Examine the movement of the linkage carefully, and this will require two people. Have someone slowly move the pedal "full range." Check for bending, flexing, movement of the bell/ engine on the mounts, bending of ANY part of the system, all the way from the fork to the Z bar, all of it. (I once had a Z bar tube crack and reduced movement)
If this looks OK, look at the linkage for leverage/ advantage. Realize that a lever system obtains maximum movement around an axis when the lever and the pushrod are at 90*. If you have some wrong link or Z bar etc you may have wrong angles and losing movement
If all this seems OK, there's only one thing left---pull the clutch, disk, and flywheel, and the TO bearing and go find a press you can use to test the movement. BE CAREFUL doing this
