I need to report back on this thread too. Along with the hoppy rear end, I've also had issues with the clutch takeup being grabby. I decided to try "resurfacing" the clutch by revving it up and slipping the clutch a couple times. Not the best way to prolong the life of the clutch, but I'm happy to report that all my clutch grabbiness is gone, as is the hopping rear end. The clutch doesn't slip at all, either. I think the PO (who was a female) probably had the clutch redone and then never really drove it hard. Over time deposits built up on the mating surfaces making for inconsistent engagement.
