I've got 82,000 miles on my '81, I'm the original owner, so I do have a complete history on the bike .
I replaced the timing chain at around 45,000 miles, for a noise, that turned out to be the transmission bearings being damaged by water getting into the transmission .
All of the other parts to tension the cam chain are original .
After hearing about other bikes with cam chain noise, I am tempted to order a cam chain replacement kit from Motobins, with my next order .