I drag raced a buddie of mine's big ol' 93 XR650L.
(motorcycle) First off, he did beat me. But not by much! I would pull him in first gear, but after midway though second gear he would begin to pull on me. Off he was, from there. The 400EX hung in there really well considering, its a quad.. the bike has a 250CC advantage.
Then we did a top speed test with my quad. She ran about 68MPH. (bike has speedo)
Just thought Id share this. I must say, the XR didnt have as much torque as I thought it would.
The front end on my 400EX is easier to lift than the XR's! (given, the old XR does need a valve adjustment)

 

Its the gearing. If the XR would of changed the gearing for lowend,,it would of been a different story.