My friend is thinking about buying a 2004 YZ 450 for $1000. It seems to be in good shape but the guy says it needs new valves. And if it needs valves then it probably needs a new piston also and a new timing chain. And who knows if the head has been cut already because if it has, won't he have to buy a whole new head also? because you can't cut the valve seats twice. He is 16 years old; as am I and if he buys it we would probably do most of the work ourselves we are hoping anyway. We would have to get someone to install the valves, cut the seats and maybe hone the cylinder. Other than that we would try doing it ourselves. So how much would it cost for new valves, piston, timing chain, and maybe a head, gaskets, ect. (pretty much a whole new top end). Do you think it is worth buying right now in this condition and then having to rebuild it. I just don't want him to buy it then not be able to do the work ourselves and him not being able to ride it because he would have to hand out a s**t load of money to a mechanic. Tell me what you guys think.