A friend of mine has an '89 YZ250 that he still rides (it's in perfect condition - better than new). The engine has been bored, ported and is always in a proper state of tune. And I hate riding the darn thing!
Not only is the throttle sensitive, but the power comes on suddenly, all within a very narrow power band. It's like riding a bike with a switch for a throttle. Without fail, every time I ride that bike I hand it back to it's owner with one of my body parts hurting or bleeding (or with real bad poison ivy - but that's a ugly story).
Anyway, the owner of this rocket powered sled is always eager to point-out that his 16 year old bike makes just as much horsepower as a new bike, which I'm sure it does. But do not confuse quantity with quality. His YZ is evil and a real handful to ride, unlike a modern bike.
Well, the 87 YZ-250 I had dyno'ed at 38 which was typical for that period as I recall (I know many mags listed around 40 for 250's then but that must either have been at the crank or advertising hype; I don't recall any stock ones getting 40 or more at the rear wheel on a dyno but I could be wrong...). Don't know what my '89 had.