Yep, I searched. I Googled. And while this is probably a common issue, I haven't found the right term to describe it, let alone search for it
The new-to-me-'07 started yesterday with 7600 miles on it, and ended the day with 8100. About 400 miles into that run, I noticed a bit of a ticking sound up front between the pipes at idle - off-idle, no tick. Of course, I checked the oil and coolant levels, which were fine, and chalked it up to my ears playing tricks on me... it'd been a long day, what with my 6'1" frame folded up on the little bike, and I was getting a little punchy.
Anyway, this morning I headed out for coffee sans earplugs, and the tick - for want of a better term - was pretty damn noticeable. Again, levels are good, off-idle is fine. I call it a "tick" because it's not a low-end sort of "knock" and definitely not a "ping". There's a dark part of my mind that wants to call it piston slap but I really, really don't want to go there since I haven't turned the bike over to the new owner.
So, I bow to the collective wisdom here to alert me to other possibilities that might be more relevant to the Li'l 250. Thanks for any pointers.