You either don't have the clutch rod adjusted enough or you have some warped
steel plates in the clutch or pack height is not correct. I would try turning the adjuster rod a 1/4 to 1/2 turn in more so it pushes the clutch out more to release, it that doesn't help, pull the clutch pack and check for warped steel plates, also check the stack height for your brand. If it is stock it is most likely a Rivera Pro clutch, go to Rivera web sight they have a lot of good info. Clutch pack height should be 1.394" to 1.425".