Odd Clutch Issue


gen1, stock with the exception of bolt-on exhaust and a few cosmetic changes.

Sat for a while (~7 months) without being used, took it out for a short drive just to get the juices flowing and the current problem presented itself. After about 20 minutes of riding and the bike gets good and warm, the clutch starts slipping under load. Within another 10 minutes, the clutch slips so bad that the bike becomes immobile. The first time this happened I had to limp it home, rpms high and low gear and by the time I got to my garage no amount of throttle, little or small, would move the bike, the clutch instantly slipped.

Bike sits another 6 months until im back from deployment and I take it to the dealership. They give it a tuneup since it sat for so long and tell me my clutch is burned up (surprise!).

I replaced the clutch - same problem
Noticed the slave cylinder moved when lever depressed, got the brace - no change
Rebuilt slave and master cylinder - still slips after ~20 minutes

At this point I'm at a loss, whatever this is it ate what was left of my last clutch and as soon as it starts slipping I park the bike so it wont do the same to this one. I'm really scratching my head on this one, please help!