I bought the CRF 450 the first year it came out, and it has been an all around good bike. The only major problem I have had was with my intake valves. Both of them began to suck in and flatten out. Even though I continued to adjust my valves this problem continued. I ended up replacing them with the Kibble White stainless steel intake valve and spring kit. Now a year later the bike runs awesome, haven't had to adjust the valves at all, and with this setup I don't get the typical early "floating" of the valves which I experienced with the stock setup. I wouldn't trade my 450 for anything....except a newer model