Hey guys recently picked up a 14' yz450f with very low hours (about 8), Being new to yamaha (coming of 14 kx250f) and new to a 450… The bike is UNREAL! It handles very well and the extra torque is great in loamy,sandy condition. I must say I'm very impressed. A couple of things i would like to address…. Are 450's normally a bit harder to start then 250's? Ive noticed it has taken me 4 or 5 kicks to start when cold (using choke). When its hot, it starts first kick. When the bike has been sitting for about an 1 hour (in between practice sessions), I could only kick it over using the choke again… (live in australia, so the weather isn't cold). How long do you guys like to wait before replacing the top end? Im thinking around the 50hr mark? Im pretty strict with maintenance doing a air filter every ride and oil/filter every 4hrs.. How many hours have you guys got on your 14 yz450f? any problems? Thanks Jack.