2010 450 knock

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?

No one has heard of any knocking problems huh? I'm also wondering if the ECU could be glitching, causing detonation at an idol?

No one has heard of any knocking problems huh? I'm also wondering if the ECU could be glitching, causing detonation at an idol?

You didn't sneak a turbocharger on your 2010 model without telling anyone, did you?:busted:

Seriously though, I've never heard of that. you went to a lot of trouble replacing pistons, etc. Must have needed them anyway?

good idea going back to stock setting. ran good for 2 miles, strange.

a few things to try;

- fuel OK? try different fuel

- like you said, maybe it's the ECU . . trying another one would verify that (of course that's probably a non-returnable item though!)

- double-check that a cam is not 1 tooth off

You didn't sneak a turbocharger on your 2010 model without telling anyone, did you?:busted:

I'm leaving that up to someone else! I timed it correctly but ill make sure it didn't jump when I take it apart. If I have to I could probably find a buddy that would let me try a different computer.

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?

Just a shot. Maybe the oiul filter is clogged? If a new oil filter, did you put it in bakwards? Probably not, but just checking.

Looks like the cams have jumped quite a few teeth, timing is way way off. That explains why it won’t start now but I’m still not sure about the knock. I’m pretty sure the valves weren’t hitting the piston. Could the chain have been clattering before it skipped?

Looks like the cams have jumped quite a few teeth, timing is way way off. That explains why it won’t start now but I’m still not sure about the knock. I’m pretty sure the valves weren’t hitting the piston. Could the chain have been clattering before it skipped?

Yeah especially if it was stretched/worn.

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