Motor Clank in top end

[AtvKid4Eva]

Hey guys my neighbor has a stock 400ex. It has a loud clank/tick in the top end at idle and it dosent go away even with throttle applied. Ive adjusted the valves several times so i don't believe they are causing it. I'm thinking either the timing chain is stretched or the chain tensioner is bad. I know when he reinstalled the tensioner her never took the preload off before tightening it so maybe it just wore out. any ideas?

[Colby@C&DRacing]

I agree you are on the right track I would lean towards the tensioner

[AtvKid4Eva]

Thanks Colby! ill look into it tonight

[NacsMXer]

Here's what a 400EX engine sounds like when either the timing chain is stretched or the tensioner goes bad (loose timing chain). Does it sound similar? I would check out both.

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/z1BCcurRlLY" frameborder="0" allowfullscreen></iframe>

[AtvKid4Eva]

yep, sounds exactly like that ^^

[AtvKid4Eva]

Well i took the tensioner out and it is the problem. The spring is so worn out it wont even move the plunger.. The chain had no tension at all!