So for us newbs who are looking for their first, 2nd hand bikes, what is an acceptable number of KMs before needing to consider engine wear and tear/rebuild, and extensive mechanical work which we probably would have no idea on? What numbers should a buyer be wary of? What does the 'excessive number of KMs' depend on? Are engine rebuilds worth it? Are high-KM bikes worth it for newbs who aren't into the tinkering and improving? How does one learn more about this? Couldn't find any threads (direct me if you find one and I used the incorrect search terms).