I am all about new stuff. If I buy something used, I automatically think FULL rebuild. Nothing like spending cash on something, going to all the trouble to make it mount up and fit to take it out one time and have it break on you. Now you have to fix something damaged.
I've been a dirt bike guy for a while. It's a dirt bike. They are usually selling it for a reason or they stopped riding it for a reason. If you're going to race something, I HIGHLY recommend you don't just bolt it on and go race. Riding a dirt bike in the woods is a heck of a lot different than racing it on a kart. We spend a lot of time in that upper RPM range for a long period of time.