[Darren69]

If the plain plates are clean, rust free and flat and the friction plates not tanged, maybe look if the basket is notched? When the clutch on my S4 was grabby when I first got it, the plain plates had a bit of rust where it looked like half an inch of water had stood but after rubbing down and cleaning they were much better. Generally though the standard clutch is pretty poor. I don't know from memory if the S4R got ally basket but they are better than the steel ones but only really improve the change action. I binned the whole lot on mine and fitted a DP SBK '08 spec slipper and tbh its night and day different and so much nicer in every way. There are a few things you can do that might improve things with the standard one but it sounds like you've experience with these and probably tried them already. Shuffle the pack, clean everything, reverse the friction plates, file the tangs. All will help but I've not tried the grease method ! That does sound like it could be a real slipper clutch.