it is time to replace the sprocket(s) on my 03 yz 450. right now it has an o-ring chain with a 14/50 set up. the rear sprocket is showing wear but the front seems ok. i probably will go back to the stock gearing (14/48 right??) which means a new chain as well. so my question is: what would be the best way to go, is it ok to change just the rear or should i change both? what is the best sprockets/ chain to go with, without emptying my pockets?? thanks.