honda trx250r

I think it's more give or take. If you do regular riding on a 250R it isn't an issue. There have been issues with frames cracking, but you have to understand in the same light, a lot of people mod them then MX them with stock frames and case jumps and everything else so they are just asking for it.
 
Now a days, yes. Those frames are over 20 yrs old!!!! When I first got my r, I never had a problem until I'd had it for 4 years, then it seemed like a new crack would appear every other week. The most notorious place for a crack is around the swingarm bolt but over time you can find them about anywhere
 
the most obvious place is at the lower brace on the sub frame. If they guy your getting it from is over 250lbs and you think he had MX'd it, look around the swing arm pivot area where the sub frame attaches. This is caused by him casing the bike and him hitting the seat with a BIG butt.