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XR 250 timing chain noise 1995 md30

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hello, i've had this bike for almost a year and not long after i bought it it started making a clacking noise when cold, then the noise would stop after the bike is fully warmed up.

i changed the timing chain and put in a new original one from another bike which was exactly the same, but i couldnt find a tensioner so i left the old one in.

now after almost one month im starting to hear ticking noise again, not so lound but i could hear it if i listen closely. do you guys think its because of the old tensioner?

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A chain taken from another bike is not "new". How much engine time/miles did the donor engine have on it? The donor chain may have only been slightly less stretched / worn that the one you replaced it with.

When changing the chain, you reset the auto tensioner, right? Looking at the tensioner wedge position before removing the old chain and comparing its position after resetting it with the donor chain, how much difference in wedge height above the tensioner was there?

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I didnt mean taken off another bike sorry, i bought it new but it was supposed to be for a honda silverwing 600.

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My problem was i took it to a mechanic when i should have worked on it myself. He said the tensioner was ok. I thing im going to take it appart again and check. But im sure the chain isnt a problem because it is brand new from honda dealer, and it was running perfect until 2days ago when the bike gets warmed up it make tappet noise, and when it's dead cold it makes chain ticking and backfires too much

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Be more clear on "it backfires too much". What are you calling a backfire? Is it popping out the exhuast on decel when letting off the throttle or are you getting a KA-POW......?

Hearing a little tappet ticking is normal when the valves are adjusted properly. Its when you don't hear them at all that you need to be concerned that they may be too tight.

Popping on decel may be just a carb setting issue. Could the mechanic have removed the carb when he swapped cam chains? Not getting it sealed in the carb boots good and causing an air leak. Otherwise, try adjusting your fuel screw out to clean up the decel popping.

If its a loud KA-POW, that says a timing issue to me.

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Well the first two weeks after he swapped cam chains the backfire was normal because i already have an air leak issue in the carb. And the bike runs normal even when not warm.

But the day i started hearing the chain ticking again when i turn the bike on in the morning the backfire on decel got really loud and the bike wouldnt run properly until its fully warmed up.

And yes you are right the ticking is normal but it only gets loud right before i start having timing problems. I think my problem is with the tensioner, is it easy to fix or better get a new one?

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I would certainly check it yourself. Set the engine up to TDC as if you were going to check your valve clearances, take the valve cover off and see if the cam sprocket timing marks line up with the head like they should. Look at the current position of the tensioner wedge.

The only thing I can think of that can go wrong with the tensioner is the spring has been known to break.

Edited by Trailryder42

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Im going to print out the manual and start, im sure the spring isnt broken but maybe it needs to be changed.

Thank you for your help. Ill get back with what the problem was. The last thing i want is a bike i cant ride in the summer

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I took it to the mecanic again as he said he'll do it for free because the original problem wasnt solved. He reset the tensioner and did a valve clearance, the bike is really faster now and there is no more backfire, at all. It used to need warming up before it can run normal.now even when its dead cold ot runs perfectly. The timing chain still ticks a bit when i turn it on maybe the new chain is shot.So trailrider was right i guess he forgot to reset the tensioner the first time.

But is it normal for the bike to suck air from the oil stick hole when the engine is running?

Edited by exray

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But is it normal for the bike to suck air from the oil stick hole when the engine is running?

The ticking you're may not be the chain. The valves can tick, even when set correctly, its normal.

As for the system sucking air when the dipstick is out, I've never really noticed. So if it is, it isn't much. Lets see what others have experienced.

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Yes, single cylinder engines produce a lot of internal vacuum and pulsing as the piston goes up and down.  That is why it's important to make sure the breather system is properly installed.

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i agree, tho after some miles with the perfect bike.. it's going back to the way it was. 2 good days have passed now the timing chain seems to be getting loose again. the backfires are coming back. and it's getting pretty bad when cold again. im guessing the new chain got shot because the mechanic didn't reset the tensioner when he put the new chain on. or it could be another problem that i dont know about..

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