steady, droning speed on the flat isn't an issue if it's geared for the speed. i had a plated KX500 that i rode from los angeles to san diego and back a number of times. it was geared a bit high, but it'd cruise at 70mph off the pipe. i'd spend 90 minutes without changing speed. never had an issue. didn't even get horrible mileage. i did have one soft seize, but it was in cold weather (wasn't jetted for it), long time on the pipe up a grade. had the jetting been appropriate for the weather, it'd likely have been fine. now, what steady, droning speed is an issue for is me losing my mind with it.