The noise can be just old oil. I also find full synth oil makes the motor noisier. I use Castrol 4t and the oil stays in the cam chain tensioners longer. Quieter on start up.
As for the lurching, you may have to sort the carbs out. Do you know what jets are in it?
I would recomend getting a set of jets from one of the recomended sources around here, be carfull installing them, check the float level (precise) and check the carb vent hoses are venting in the right area. I also fitted a air damper (shield) around the front of the carbs (Rottwieler air filter) cause I had a bit of hunting at 100 kph. I think the air needs to be more still around the air filter area.
990 Adv 06, Aprilia Tuono 03 Racing gen 1