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Engine Noise...Help.

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Moderators...the issue isn't make/model specific, I'm just trying to identify a noise. Please don't move it as it gets more traffic here.

 

 

I have a 2004 RM-Z250 that I just rebuilt the head on. I had JM Racing cut the seats, I installed new Kibblewhite Black Diamondicon1.png Valves, new springs, seals, etc....I reassembled it yesterday and it started right up. After a few minutes of running, it started making a intermittent sounds that sounded to me like the piston is bumping the valves. I didn't mess with the jug at all, and it was not making this sound prior to the rebuild, so I don't think it's piston slap, but if the piston was coming in contact with the valves, wouldn't it make that noise every revolution? See video below. Any help is appreciated. 

 

https://skydrive.liv...hint=video,.mp4

 

The noise occurs @ 43 seconds and happens twice.

Edited by RAGEman

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Nearly all mechanical issues are bike specific. Unless you are talking bars, helmets, tires, crushed exhausts amnd why a 2S is better than a 4S

 

The desire for 'traffic' is outweighed by forum organization.

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I dont normally visit the suzuki forums but ran across this and decided to give it a listen, sounds like timing chain and/or chain tensioner issue to me.

Thats the first place Id start and probably wouldnt ride it until its fixed. Good luck!

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I dont normally visit the suzuki forums but ran across this and decided to give it a listen, sounds like timing chain and/or chain tensioner issue to me.

Thats the first place Id start and probably wouldnt ride it until its fixed. Good luck!

 

My point to the mods exactly. No one visits these forums...

 

Anyhow, thanks for the reply. The tensioner seemed to engage properly upon installation. I heard the clicks and the chain went tight. But I agree, that seems more likely than PTV  because it's intermittent. I'll pull it apart again tonight, I just wanted to get some ideas before I did. 

Edited by RAGEman

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I was thinking tensioner as well.

 

So, I fully understand how this tensioner works, and it seems to be working properly, but I've had several people mention the tensioner, so perhaps I'm missing something. Doesn't it either work or not? There's no in between is there? It engages and clicks, and locks as its supposed to, isn't that pretty much the extent of the diagnostics for it? 

Edited by RAGEman

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As was said after listening to the noise in the video it sounds like a timing chain issue, too loose, stretched, maybe bad spot(s) in the chain. Possibly a tensioner that doesnt hold tension continuously allowing to much chain slack, its a good idea to replace both parts. The automatic tensioner can totally fail but sometimes theres a spot as it adjusts that doesnt hold and can slip allowing a loose chain.  It needs to hold tension against the chain continously so it moves the guide to tighten the chain.

 

Some guys like manual cam chain tensioners and one of the good things about a mcct is that you can actually monitor the chain wear, slack or loosening by how much adjustment it needs since you are the one who is doing the adjusting. Some guys like that and some guys dont want to bother with having to adjust the cam chain, but using the mcct the cam chain adjustment stays where you put it. Hope that helps.     

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Check the spring on the decompressor.if the weight is hanging and no tension-thats it

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Check the spring on the decompressor.if the weight is hanging and no tension-thats it

This was a thought of mine as well. Its functioning properly though.

I bought a new chain and a new head gasket. I'll reassemble this weekend and keep you posted. Thanks for the help and suggestions. Much appreciated.

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Nope. Re-assembled today. Same story. I guess trying a new tensioner is all that's left. I'm baffled by this. It wasn't making this nose prior to the new valves, that's why I'm reluctant to buy a new tensioner, but I'm out of ideas.

My rule has always been "if it wasn't making that noise before you messed with it, check the last thing you touched" but I don't see how I could have done something wrong and it still run like that. If I was off a tooth, it wouldn't run right. If the piston and valves were connecting, it would damage the valves, and would connect with every revolution.

I did notice that the noise would occur when I could hear the idle drop a little lower. If I raised the idle, the noise goes away or doesn't occur at all.

Edited by RAGEman

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My guess is tensioner. Not much else that could cause that. Only other things would be a crank bearing going bad,oil pump losing prime or the decompressor. the decompressor coul be ruled out by removing it completely. The oil pump-would have to check pressure,check screen or look for scoring/seizing. Bearings would show up as play or particles in oil. I have seen people drop a wrist pin clip in he crank and make noises like that,but on a 4 stroke-it would go back to the magnet or the screen. You can make the stock tensioner into a manual tensioner. Pretty easy to do-just put a bolt and lock nut in place of spring. There is some explanations on TT or on utube.

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My guess is tensioner. Not much else that could cause that. Only other things would be a crank bearing going bad,oil pump losing prime or the decompressor. the decompressor coul be ruled out by removing it completely. The oil pump-would have to check pressure,check screen or look for scoring/seizing. Bearings would show up as play or particles in oil. I have seen people drop a wrist pin clip in he crank and make noises like that,but on a 4 stroke-it would go back to the magnet or the screen. You can make the stock tensioner into a manual tensioner. Pretty easy to do-just put a bolt and lock nut in place of spring. There is some explanations on TT or on utube.

 

The home-made tensioner is a great idea. Don't know why I didn't think of that. I'll try that before replacing the one I have. I guess I can pull the decompressor while I'm at it. It takes all of 2 seconds and eliminates a possible cause. Other then that, I guess I need to take it to a shop. I'm tired of screwing with it, and throwing parts at it is just costing me money. 

 

Thanks for you help!

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Did you happen to remove the flywheel. I had a noise like that on our old bike made a ramdon noise .Retighten flywheel  noise went away. It took hours to find.

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Did you happen to remove the flywheel. I had a noise like that on our old bike made a ramdon noise .Retighten flywheel  noise went away. It took hours to find.

 

I did not remove it the first time, but while trying to investigate the sound, I pulled it. 

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Interesting development. So, I started it up today, and it of course was making the noise. I started playing with the idle, and when I turned the idle up ever so slightly, the noise stops. See video below.

 

https://onedrive.live.com/redir?resid=3DB88069182C0939!953&authkey=!AI-6-KjtsAPBLDI&ithint=video%2c.mp4

 

So....can someone go out to their bike and do this same excersise and report back to me? If it's just a low idle issue, then something is slapping around when it idles down and shakes a bit. This may happen to all bikes, I don't know. Help?

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That's the decompressor slapping

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That's the decompressor slapping

 

OK. So, I had some spare time yesterday, and I decided to pull the decompressor and see if it still made the noise with it removed (I didn't intend to run it this way but for a few minutes) 

 

So I pulled it out and it was incredible hard to crank, and it wouldnt start. I eventually gave up, and put the decompressor back in. Now, the bike kicks over somewhat normal, though it sticks occasionally, and the bike is very hard to start. Did I re-install this incorrectly? It's a pretty simple mechanism, i don't know how I would have messed it up. I got it to start eventually, and it ran fine, but i had to kick it 50 times. Any ideas?

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