I had a nice blue Yamaha TX500A back in the early 90's,the one w/ the 2-piece cylinder head.I did a valve job and fresh rings,adjusted the cam and balancer chains as much as possible and kept up w/ all the re-torque on the cyl. head,etc.I put 10+K long distance miles on it w/o any problems before I sold it 2 yrs. later w/ no leaks from the cyl. head gaskets.I liked the torque curve of the engine,it even had the stock mufflers.
They just need regular maintenance & adjustments and don't survive well w/o them.