Slipping clutch -gpx750

Hi guys.
I posted this question in the 'retro /resto' section but perhaps there are not many of these bikes still around these days.
Anyway, my problem is a slipping clutch. I know there are many reasons why this could be the case so trying to narrow it down a bit.
I have been rebuilding the bike for a while so I don't know if the clutch was slipping previously.
The hydraulic clutch oil has been changed.
The clutch seems to work well when cold but then slips when warm. The warmer the engine the worse the clutch slip.
Any ideas? Thanks
Glynn
I posted this question in the 'retro /resto' section but perhaps there are not many of these bikes still around these days.
Anyway, my problem is a slipping clutch. I know there are many reasons why this could be the case so trying to narrow it down a bit.
I have been rebuilding the bike for a while so I don't know if the clutch was slipping previously.
The hydraulic clutch oil has been changed.
The clutch seems to work well when cold but then slips when warm. The warmer the engine the worse the clutch slip.
Any ideas? Thanks
Glynn