thats a YAMAHA for you
THrow that engine into a quad frame and it will win by a lot less. I hate to admit it, but dirtbikles are faster. I'd never buy one though. You're forgetting that even though it is old, the YZ490 is a two stroke and will put out more power than a four stroke of the same displacement. Compare a banshee to a raptor 350. THe banshee is the fastest stocker of all time and the raptor is well........ slow. 450r is still a good bike though.