Hello Dear Community,
First I apologize in advance, my English is not good and I use the Google translation, to post my question,

Yesterday I bought myself a birthday present, T�n�r� 08 with 60K km on the clock,
I wanted this bike for years
I do not know the bike or its normal engine noise but I think its sound is not healthy,little more on the left side.

The engine works and responds well, today I replaced the air filter and oil filter and spark plug, at the same time I unscrewed the cover of the box on the right to check a common problem recommended by a friend to check, this nut that holds the gears near the clutch mechanism (picture attached),


I tried to find out if it is released, but it's not, it's very strong not loos so I closed the cover, and filled oil.

So after I moved the bike I noticed the noise more noticeable on the left (after that I saw on the right side everything is fine)


I would like to ask you, what are the common causes noise on the left side of the engine? What would you recommend that i check first?

Thank you very much in advance

Timing gears/chain/tensioner is on the left, but I don't think I've ever heard of anyone having a problem?

Decompressor pin loose or broken? - Known issue, but not that common.

Alternator? - Unlikely.

Starter motor gears and sprag clutch?

Gearbox???

Can you describe the noise? Knocking, tapping, rattling, squealing... Might help narrow things down a bit.

Use a length of hose as a listening device to locate the exact position of the noise.

It's also worth noting that the upper of the two bolts the hold the exhaust heat shield on is too long on early bikes and taps against the exhaust pipe at certain engine speeds.

http://www.xt660.com/showthread.php?t=18033

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Thank you,
its really hard for me to describe what is the noise sounds like, but i uploaded a video to record the sound, hoping to be able to understand something of this.
While I recorded, I touched firmly to the bottom of engine with the phone body, and then to the top of the head, both sides of engine, the sound changes.

https://www.youtube.com/watch?v=nKbuSSc6PTQ

Difficult to be specific, but I'd say the noise is coming from the top end. When you moved the phone away and there was less resonance interfering with the sound quality, it very much sounds like loose valves.

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Thank you very much,
certainly, the engine valves need adjusting, It is planned for tomorrow,

the noise that worries me is the noise that comes from the bottom (at 1:24 for example, or from 1:37 in the recording), I know it's hard to understand the recording and I really appreciate any help in diagnosing the noise before I start to dismantle.
after the valve adjusting ill do another recording, (if hopefully the top end noise will disappear).

thanx again for your help

For everybody's information, this issue was resolved and covered in this thread.

Don't really know, but it sounds like a sloppy cam chain to me. Possibly a worn-out one, or broken tensioner at the bottom?