Hey guys, I'm a lifer honda guy. That being said I've worked on all brands. I had an 07 yz450f motor roll in the garage yesterday, got it fixed and decided to ride it today. To a major surprise this bike was 4speed????? I thought 05 was the last year for that. How easy is it to swap motors on these and how can I identify an older motor? The owner just rides he don't keep up on bikes and this was a recent purchase for him.......I'm figuring he may be a little upset if I have to tell him his motor is 10 years old.