Still working on the XS650.
Things I've learned so far:
Fork oil seal clips and washers for 34mm forks are no longer available.
Choke shaft seals for BS38 carbs are no longer available from Yamaha.
Removing the lower bearing race from the triple tree is a hell of a lot easier than the CB750 was.
Installing tapered races in the neck is easier too.
Removing the rear wheel bearings is also super easy. (Where I found really dry, crunchy, scary bearings!)
Removing the front wheel bearings, not too bad.
Yamaha's black paint strips
real easy.
The local bike shop
will ding up the alloy rims removing 25+ year-old tires and then tell you never to come back again.
The Yamaha shop manual is pretty crappy compared to Honda manuals.
The new powder coater I went to will do a great job at a cheaper price than the last place I used.
And I'm sure there are more revelations to follow.