it all comes down to maintenance and how the bike is treated. i've seen plenty of bikes approaching 100,000 miles.

pound for pound a sportbike motor is waaaaay higher strung than damn near any car, so they're not going to last as long before they need freshened up. 25,000 miles isn't that bad if it was taken care of correctly. sadly, most people don't keep up on thier maintenance, and beat the crap out of thier bikes. hell, most sportbikes are layed down at LEAST once before they ever even need a valve adjustment.