What shape is your clutch diaphragm spring? It needs to have a convex shape i.e. not flat.
The spring would normally be concave when viewed from the outside.
Ideally, the stack height needs to be as 'high' as possible but not so great that it results in clutch slip as "clamping force" is reduced the closer the spring is to (and beyond) flat (
approximate 'spring flat' position marked in red) at the "Fully home" position, therefore, stack height is a trade-off between the lightness of clutch lever action and 'grip'. The transition period where the spring moves through 'spring' flat should be felt at the handlebar lever when the action becomes lighter as the lever is pulled back to the grip so the closer this changeover point is to the start of lever movement the lighter the action will be. If it only occurs when the lever is almost back to the grip or if not felt at all, then the stack height probably is 'low'.
Moving the fully home position also changes the full lift position so there seems little to be gained by setting the fully home position much beyond 'flat' (in my opinion).
The diagram is a copy (of a copy) from the NOC Commando Service Notes, 1979)
You can adjust it to the correct shape using the clutch spring compressor.
If the spring is set 'flat' with the compressor and held in position (without releasing the compressor) then the distance the stack height is (usually) short of what would be the 'spring flat at the fully home' position can be determined by measuring the distance from the spring to the circlip groove (or circlip) as demonstrated in the OldBritts image, below and without the need for stack height-clutch drum depth calculations and also takes spring thickness into account.
If adjusted correctly, you will have a nice easy pull. Also, try putting an additional steel plate on top of the last plate in the stack so you can just fit the retaining circlip after you install the clutch pressure plate and clutch diaphragm spring.
An additional plate can often cure a heavy clutch lever action, but as the ring of the pressure plate is in contact with the spring at approximately half distance then any alteration to the stack height alters the spring's position by approximately double the change in stack height so in certain cases an extra plate could be too much.
