XT600e weird top cylinder head cover blind screw and engine noise issue
 

Hi,

First post in the forum, but long time lurker. I have bought an xt600e 2003 model about 2 years ago. Really love the bike, actually my first big proper bike, and great fun to ride. I have no experience with bike mechanics, but I can manage working with tools and understand diagrams (electronics background).
Since last October I have noticed a weird noise coming from the inside of the engine. The bike has been very forgiving to me as so far I have only been changing oil. As the weather is getting much hotter here in Greece, the bike gets hot very easily and last two days the bike was shutting down.
A knowledgeable friend of mine helped me today to adjust valve clearance and have a look at the bike, see if we can tell where the noise comes from, but before arriving to the noise issue, when removing the gas tank, a pretty strange modification was in front of our eyes. The cylinder head cover was threaded and a blind screw exactly on top of the cam chain top was there. I called the previous owner and asked him about this and he told me that he has seen it after buying the bike, and that it had a tube running to the back of the bike and that it was losing oil from this tube, and because the oil was spitted to the rear wheel, he cut off the tube and capped the screw. I am attaching a picture of this ... device

So my first question is, if anyone has any kind of idea why someone would do such a thing and what the purpose of this thing is and if i should cap it or connect a hose to it.
And of course my second question is about the noise issue. I have recorded some videos but the noise is the same as in this video . The guy who posted the video states that it was cam chain issue, which was our intial guess, so any idea on how should I proceed in testing the cam chain or any guide available in replacing the cam chain would be very welcome.
Btw I measured cylinder compression and showed me a healthy 11.5 atm, after valve adjustment.
Thanks in advance to any response, and I promise to take serious care of my old lovely lady from now on.

Cheers

Aris

I am also attaching a video i recorder with my phone illustrating the exact noise. I start the bike with high idle, the I leave the bike running for a few seconds with normal idle and then I rev the bike illustrating how the frequency of the noise synchronizes with the engine speed. Sound something metal has loosen and hops on some other metal surface. Btw the bike has no power loss, it just gets very easilly hot.

https://youtu.be/QGE30PGseQQ

Thanks,

Aris

Hard to tell from videos, is this similar? http://www.horizonsunlimited.com/hub...eck-your-73934

The plug on top is not original.

Thanks for the answer.

I think it is different, but worth a check. One way or another It was time for an oil change so checking behind the clutch cover is not a bad idea.
From what I already read so far, the problem should either be:
a. cam chain
b. counterbalance nut
c. cam shaft bearings
d. valves
e. piston slap

I dont think it is piston/cylinder related as the cylinder pressure was tested.

Valves were adjusted and they have been found that the intake valve gap was very short. So I guess this could be the reason for the engine shutting down.

Any other idea on where the noise might come from, or how can I check already mentioned sources without opening the engine? Somehow I think that this weird top thing is related. Could this possibly be an oil cooler?

What you mean with camshaft bearings?

bearings of the cam. I ve read of a situation where noise was introduced due to play in the bearings.

Well still dont understand what bearings you are talking about, can you give me part nr?

Hi, sorry if I have confused you with my question. I looked through the manual but cannot find any part number. Maybe I have misunderstood something. Shouldnt the camshaft be somehow mounted with bearings in order to be able to move? I know its difficult to diagnose a problem only from audible noise and just from one video, I was just wondering if someone with experience has ever noticed something simlar.
Still any idea what the screw on top of head cylinder cover might be used for?

Thanks,

Aris

Here you can see camshaft between rocker cover and the head.

http://www.horizonsunlimited.com/hub...cam-worn-53548

There is no camshaft bearings.

If you suspect the camchain, try to remove the tensioner, and see if its fully extended. If not, the chain shouldnt be worn enough to make such bad noises. As a test, insert the tensioner back, and now remove the spring, insert a screwdriver where the spring was, and see it you can push on the tensioner, making it extend a click or 2 further. Insert spring and endcap, and start the bike. Does the sound go away?
Make sure to reverse this as the camchain is now a bit tighter than it should be.

Camchain-clatter often goes away as the rpm increases, opposite pistonslap.

Valves on the xt lasts a lifetime.


Is the hole in the valvecover threaded? It might have been drilled for a temperaturesensor, but it doesnt make sence with a hose beeing fitted to this.... Poor mans auto-chain oiler? :D

Thanks guys for the answer. I will check the next days for the cam chain and I ll report back. The hole is threaded. A temp sensor in the most weird place -maybe. an auto chain oiler? isnt the cam chain supposed to be lubed by the engine oil? Even for a diy oil cooler, this place dont seem to make sense for circulating oil. A friend of mine gave an endoscope camera with a 90 degree mirror so I will try to take a few detailed pictures from the inside of the hole and report back.

cheers!

He was thinking about oil coming from top back to the drive chain, as a joke ;)