Motorcycle engines don't "time" out. They can, and do, "wear" out to a point that the bike is sold, abandoned, or forgotten in a corner. That does NOT mean that it is worn beyond factory specified service limits listed in the shop manual.
Also, re-boring cylinders to maximum available oversize does NOT mean they are "trashed" if the job is done properly, and decent quality oversize pistons and rings are used. Same goes for crankshafts. Even parts that are well worn, but still within specification range, can still be re-used AS-IS for many more miles as long as the owner takes care to properly maintain and service the bike with good quality lubricants, AND ride it with a reasonable amount of care, not thrashing it mercilessly.
Some engines look quite worn, are dull and faded, maybe even weeping a bit of oil here and there, but will run longer and harder than a shiny engine that hasn't been serviced and maintained, and is abused by it's rider.