the "tune up" is a relic of the old days when you had points and a carburetor, and valves needed adjusting. these days about the only thing you can really do is replace plugs, nothing is really adjustable any more(and that's a good thing, because you don't really need to).
i learned that there are two kinds of tune ups when i worked at the saw shop. there's, "give it a tune up" which means that someone just wants some preventative maintenance done. then, there's "it needs a tune up" which means it probably doesn't even run, and will absolutely need more work done(usually a carb rebuild, or it's blown up). the former was easy money, the latter usually meant you were in for a fight with the customer after you tell them they need a new top end("it ran fine the last time i used it...5 years ago!")
