all bikes do this. it just depends on how bad. when you pull the clutch in you disengage the gear box and inner clutch hub. so, no noise with clutch in and then noise when clutch out. this says to me that the there is a problem on the gear box input shaft and or associated clutch parts (the middle). i would say in my experience it will be the gearbox bearings. if you take the inspection cover off the clutch. remove the the presure/drive plate. take hold of the main clutch center nut and see if ther is any up and down movment. if there is alot then you need to replace the bearing behind the clutch this can be done without spliting the case. if you need help to do this just post again on this thread
hope this helps
