clutch started slipping today

['73 H1 Triple]

'93 Kawasaki ZR1100 with 24.5K. Oil & filter just changed Friday. Oil and filter has been changed every 3K for the life of the bike ( The first two owners are friends of mine )

The past week, sometimes my takeoffs weren't smooth as the clutch seemed grabby. I siphoned the fluid out of the clutch master cylinder and replaced it with new DOT 4 fluid.

I changed the oil & filter on Friday with Honda brand oil in 20W-50. This was the third change using this oil.

Yesterday, everything was fine. ( 18 miles each way ) Today, a few miles from the house as I was accelerating up a hill, the rpms "jumped" in 4th gear from 4K to 5K so I reduced throttle and rode easier to work.

After work I stopped in town to fill up and when I went to take off from the light, I let out the clutch lever and NOTHING HAPPENED . I was pushing while sitting when it stared moving. I had four miles to get home and it was "interesting" to say the least. Irregular takeoffs and it slipped whenever it wanted.

I did make it home and now it's out to the garage to see what's going on.

Any ideas other than the clutch is fubar?

Jeff