That sounds like it’s the countershaft balance gear, kick start idle gear, or the outer clutch basket. Pull the clutch cover off and inspect these items. Make sure you have a retaining clip on the kick idle gear. Look for contact marks. Make sure the rivets on the countershaft gear are tight. Check the flywheel as well as you may have dropped a magnet. Check that the primary drive gear is tight and check the nut that holds the clutch basket on. At any rate…….fix it before you ride it.