I just got a new 2004 yz450f and cant keep it running. It seems to die when i go down a hill and lock up my rear wheel , as well as when i pulled in the clutch to ride the berm at the bottom of the hill, and it died on flat ground when i hit the rear brake hard and yes i did have the clutch pulled in all the way, or it also died when doing a small step up in mid air i just fell over cause it was a steep hill, it will run fine if i come to a slow stop and have the clutch pulled in but after a quick break where the rear wheel locks up or as soon as it locks up it wants to die. Is this just the idle speed that needs to be adjusted???? Also i read the manual but any break in and maintance tips. Today i just putted around mainly in second gear for about an hour, and do the piston rings really need to be replaced every five times out! Thanks for any help you can give me.