Hey Veritas - I'm new here too but I just learned a thing or two since I recently bought an '87 250x. Got a great price but it has some problems the owner didn't point out.
If it's hard to start, doesn't idle well, and/or runs a little rough that could mean something minor (as in my case - I lucked out) or it could be something big.
Look closely at the rear axle; bends, cracks, major corrosion or rust are going to cost some bucks to fix. Also check the condition of the chain and sprockets. Neglect there means neglect elsewhere too.
Pull all the body parts off if you can and really look it over. Check the air filter too. One bike I looked at was pretty spotless, until I pulled the air filter which was nasty - I walked away from that one.
Take some wrenches - 10mm and 8mm. Put them on the head bolts and torque a little - make sure none feel stripped. An old shop trick that works great is to spray the head gaskets (and others) with some spray on deodorant that comes out white. Crank the engine, rev it a bit, and any oil leaks will be immediately noticeable.
Good Luck!
