after some 10w 40 motorcycle oil (safe for use with wet clutch)
636CC Sports bike
Here you go.
The best oils there are the Silkolene Pro 4 and Comp 4, Motul 300v, Redline, Amsoil, Shell Advance Ultra 4*and Castrol Power 1 Racing. The Motul 5100, Castrol Power 1, Shell Advance VSX and Silkolene Super 4 are good cheaper alternatives.