How hard are you on the clutch?
These problems stem from clutch abuse (lots of heavy-throttle clutch-slipping and/or dumping the clutch at high revs) or defective/cracked parts.
If you have already fixed the clutch, just don't be too hard on it.
Also, there is a safety aspect to consider. If you are going to be rough on the clutch, consider adding a scatter blanket.