When I bought the bike, oil leaked from two caps, but the problem was fixed on the first appointment.
When the engine warmed up, a ticking sound was heard as if the valves were knocking. After 3 fruitless visits to Yamaha dealers, who adjusted the valves, the problem was fixed at the official dealership's workshop. It turned out to be large gap between the piston and cylinder, resulting in piston slapping on the cylinder walls. Later I found out that many later XT models had it, due to old cutting tools used in the Yamaha production line!! Of course it was covered under warranty.
Another problem was the backfire, at any RPM, when closing throttle. Solved again, after much drifting around, by the official dealership's workshop...
I bought the bike for its reputation to be "immortal", immune to problems. I have to say that after almost a year of owning it, I got to feel confident about it. Do I have a Monday model? Is it normal and acceptable in terms of quality for such a big company to accept old cutting tools in its production line?
Plus, why not a replacement bike for the time your problem is fixed, under warranty? Things they should consider...