I was just leaving the truck when my 2010 yz450 started knocking. I shut the bike down and looked it over. Everything seemed fine, it had oil, compression and and tranny and clutch seemed to work fine. I started the bike and it still knocked but soon died and would not start again. I took the head and cylender off and inspected everything. The rod and main bearings were fine, as well as the valve trane. I replaced the piston and rings, set the valves and put the bike back together (hoping that the knock was detionation due to a tune i recently downloaded with my gytr power tuner. I downloaded the stock tune and the bike ran great for about two miles and then started knocking again. And again i killed it, started it once and it would not start again. Has anyone heard of this? Could it be the auto decompression sticking? Where should i start?