If you wnet ahead and got some bad advice and used an Automotive synthetic it may be loaded with "MOLY". very bad stuff for a Wet Clutch.
Also, be certain your not accidentaly resting some weight on the clutch with your fingers, had a busa a few weeks ago in the shop becuase the customer was certain his clutch was bad. There was nothing I could do to make that clutch slip. Turns out if you just apply a few ounces of pressure to the clutch under power it will slip pretty easy.
Modern Synthetics ROCK. Just make certain your using a bike specific synthetic and go the distance. Don't Mickey mouse around with Blends and Semi-Synthetics your just wasting money without any benefit. Go to a Full Ester Based Synthetic From like Silkolene, Motul, Etc. They are expensive, but they are truly Synthetic and work wonders on your tranny.
Good news is that unless your clutch is just fried from abuse before you changed your oil, you should be able to just drain your oil, replace it with a motorcycle specific Dino or Synthetic and you should be good to go. Assuming of course that it was friction modifiers in your oil causing problems.