first thing, do not pull the starter lever when the motor is running. It will cause premature wear the the starter plate and the starter clutch lining.
If your taper looks like shit then that IS your issue. Your clutch will never mate correctly with the crank with a damaged taper.
Sounds like there is also an issue with clutch bell spacing. Make sure the clutch bell has some float in and out and the correct series of circlips and spacers are being used. The bell should spin independently from the crank unless the clutch is engaging it.