What brand, weight and type of synth did you use?
If it's not a motorcycle-specific oil, this could happen.
Automotive engine oil has friction modifiers in it which will cause your clutch to slip. Motorcycle-specific oils don't have these additives in them.
Royal Purple for motorcycles.Ime, you're right. If you see friction modifiers on the bottle, the wet clutch won't be happy. Dino oil or synthetic both work fine for me (as long as no friction modifiers).
Went back to Dino and it was fine for a while.