Thanks for the reply.
When I bought the bike the engine was siezed and the clutch was removed with the washer missing. After bebuilding the engine with a new crankshaft I made a washer to suit and followed the instructions but it would not stay on the taper. I eventually realisded that it was bottoming out on the inner thrust and wavey washer. As an experiment I machined a few thou off the inner face and it seated fine and lasted for a few hundred miles.
I bought a second hand clutch inner, swapped the clutch bits and it worked ok even lapping it gently as reccomended. However this one only lasted for a few miles before it came loose and the resultant push home. The bore of both inners always looked slightly ragged and were not smooth so suspect that the replacement may have also been faulty.
Good to hear yours has lasted, if someone had a keyway cut do some engines suffer from this problem? A new clutch inner is sounding very attractive!