cam chain symptoms
 

Hi again mates:

My 98'xt 600 E has done 40000 kms.
i've read other post in the xt600 forum but there's a lot of info of the xt 660,very similar to xt600 engine but what with the xt 600 E?

When i turn the engine on,it starts to sound really funny,very similar like loose game valves and after 4 minutes or so,the engine's sound it starts to fade out.

What could be wrong here?

-wear in the timing chain?

I checked the game valves like a couple of months ago,but the sound is still there.

any comments?

thanks mates

You can check easily, remove the chain tensioner carefully, make sure it does not change position when you remove it, and look how many marks there are left for the spring to tension the chain. The last 4 or 5 marks will not be engaged automatically by the spring. If that is your situation, you can move the tensioner forward 1 mark by hand, put it back and start the engine and listen.

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Fred, XTZ660, Holland.

Don't be overly careful removing the cam tensioner. Just first remove the center nut so the spring disengages. Tensioner will then remain in the same position when you remove the two allen bolts and the tensioner.

Auke

Hi,thanks for the replies,i've checked the tensioner and i saw the marks and it was exactly just like you said in the 5 last position.

Then i push the thing of the tensioner in,and the sound has gone,(i put it in the 3 last mark).

Should i change the chain?

and if so,what about the tensioner?i think the only piece that wears off is the spring of the tensioner.

What do you think?

Thanks again mates

Theoretically you should change the chain, but you can also run the bike for another year or so like I did for 30.000 km., so no hurry.
I suspect that the performance at low rpm wil decrease a bit with a worn chain, but at high rpm it's a bit better. Did you notice that also?
It is said that some racing tuners deliberately put the camshaft one tooth too late to increase high rpm power.

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Fred, XTZ660, Holland.

Moving the cam timing out by one tooth can be done on some bikes but you have to be very careful.

If top end power is increased, it will be at the expense of some midrange power. This "trick" is not free horsepower, it is only moving the power around. To do it properly, you're better off having adjustable cam sprockets. I imagine you would get a better result with a DOHC engine where the inlet & exhaust timing can be moved independant of each other compared to a SOHC engine where the relationship between inlet & exhaust is fixed.

A god way to envisage this is to imagine a dyno read out - it's not the peaks that matter, it is the "area" under the hp/torque line on the read out that counts.

Steve

Thanks again.

The mechanic broke the cam shaft because he tried to remove the crankset nut(19 mm)by holding the cam sprocket with a screwdriver.
In the end,he replaced the entire cam shaft for a new cam shaft.

The weird thing is:

I noted that the engine's oil has raised 20 degrees celsius at least and it sounds a bit louder(tic tac tic tac).

Could be the NEW cam shaft? what i mean is because it is new and still it hasn't got the braking in period,and the oil is hotter because of the braking in?

thanks for replies

check cam timimg.
if the mechanic has fitted the cam sprocket in a wrong position, the engine might overheat.

order the clymer manual from amazon.com, everything you (or your mechanic) need to know about this is in there ( ISBN 0-89287-546-1 )

best regards
klaus

Thanks for that klaus,i'll be checking in the service manual to check the correct cam sprocket position.

one more question klaus,if the cam sprocket is not in the upper position but the timing marks are aligned,is this what you think that is wrong and the engine might overheat?

Thanks again

[This message has been edited by xt performer (edited 12 March 2004).]

Hi, experts guys, I wanted to revive this thread so you can show me some light:

I have a XT 600 and I rebuilt the upper engine, meaning cylinder, piston, rings, valves seals, seats etc. because of gray smoke. I noticed that the cam chain tensioner was all in (in the last mark) but I did not change it. After all that the bike had a failure at 1/4 throttle (2500 rev). It sputters and shakes as I accelerate more and more, I feel a lot power but a lot of vibration too.

Question: is it possible that the timing is a little bit off due to this slack?

By the way I check the carb, the plug, the gas, the filter and everything was right.

Dont think thats why. But with a chain stretched that far, I would replace it asap, before it takes out your newly rebuild engine aswell.