firecracker22

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Oct 23, 2000
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I've been hearing a strange rattling noise as I ride--not sure what it is. My bike is still fairly low miles and has had regular maintenance (as much as I know to do that is) so I hope it's not something broken. It seems to be underneath the seat, so it's motor/gearbox rather than a wheel/tire problem, and I notice it during both acceleration and deceleration. It sounds very similar to a loose chain but I have already checked that. Any ideas of where to look?
 

firecracker22

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Oct 23, 2000
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No, it doesn't seem like that kind of rattle. Plus it's too rich, I'm jetting down step by step right now, and still fouling plugs. It's close though. Anyway, I don't think it's a ping. It really doesn't sound like one.
 

MWEISSEN

Whaasssup?
Mi. Trail Riders
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Dec 6, 1999
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Here's some other ideas:
1. Loose bolt on expansion chamber or silencer
2. Broken mount on expansion chamber
3. Something loose in the silencer
4. Did you put the air filter clamp on correctly?
5. Loose lower chain tensioner wheel, or bad wheel
6. Something loose under the tank

That's about all I can think of - hope these help you find the problem!
 

DualSportr

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Aug 22, 2000
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Is it the same if the clutch is pulled in (when riding)? What about with the engine running but bike stationary? Does the frequency or pitch change with the engine rpm?
 

firecracker22

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Oct 23, 2000
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Clutch doesn't seem to make a difference, and it doesn't make it if it's sitting still and running. As for the pitch, it's not very loud, so when I'm on the gas I can't hear it. I just catch a little sound every once in a while. It's very annoying. I don't see how it could be chain slap when my chain is properly adjusted.
 

weimedog

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Damn Yankees
Nov 21, 2000
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It almost has to be the chain.

Usually chasis vibrations such as broke exhaust mounts and stuff will "buzz" when you rev the motor at a stand still as well as when you ride....they are vibration related.

The chain might be just rattling against the chain guide, chain guard by the counter shaft sprocket, or possibly on the frame. Look for rubbed spots. As a chain wears it can have more side to side slop and give you that chain whip that annoys until a new chain/sprocket is put on the bike.

If the motor was pinging you would also see evidence on the plug. If there was internal transmission issues enough to worry about, you would see evidence in the transmission oil.

I had a water pump break a few years back. it rattled for a little while while I was trying to field-figure it out... LOL until the MOTOR rattled and stopped! (Honda)
 
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firecracker22

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Oct 23, 2000
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Don't scare me like that! I don't want my water pump to go bad! Hopefully it is the chain. I will look it over. I checked out the pipe and silencer, it feels solid. Not sure what else it could be.
 

Fred T

Mi. Trail Riders
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Mar 23, 2001
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I think it might be your chain, it seems to be common with KTM's. Last Friday we had 3 250 EXC's riding together and all 3 of them made the came clattering noise. Our chains were adjusted fine, it just makes that noise. It's a KTM thing, you'll get used to it.
 

Jaybird

Apprentice Goon
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Mar 16, 2001
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Charlestown, IN
FC,
Be SURE you check out your rear sprocket bolts. They can loosen even when loc-tited.
Are you adjusting the chain by what the book says? If not, what is your procedure?

LOL, MXFastguy! :)
 

DualSportr

Member
Aug 22, 2000
527
0
The chain rubs on a bunch of stuff even when it's adjusted correctly.

If you've eliminated all other possibles, make yourself feel better by riding the bike down a hill with a dead engine. If it's the chain, you'll hear it right away!
 

MWEISSEN

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Mi. Trail Riders
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Dec 6, 1999
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Fred, I was one of the 3 you're talking about, and I don't remember any chain slap noise. I think I'm maybe just used to it and don't even register it.

I guess I tend to agree with the others now, especially since you don't hear it while sitting still, and it sounds like you have to concentrate to hear it..
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
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Sometimes when a bike is rich on the pilot jet it will make a noise like that-its a bit like the cylinder hydolocking with the excess fuel-try adjusting the airscew leaner and see if it reduces.
 

WoodsRider

Sponsoring Member<BR>Club Moderator
Damn Yankees
Oct 13, 1999
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You could try foam earplugs. ;)
 

LoriKTM

Super Power AssClown
Oct 4, 1999
2,220
6
New Mexico
I notice that my bike will make a slight rattling noise if I happen to have the clutch pulled in while the rpm's are near the power valve opening set point. I thought the noise was strange at first as well, but Dave says his bike does the same thing, right at the power valve transition from closed to open. It worried him enough when he got the bike that he called the shop about it. Seems to be one of those things that is more noticeable after break in.

I also recently found a small hole in my exhaust pipe that was causing a hollow rattle sound. It was only noticeable at certain times too. It's amazing how attuned we get to our bikes, so that the slightest creak or change in sound will set off the alarm bells!
 

firecracker22

Sponsoring Member
Oct 23, 2000
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No, I took that plastic guard off.

I will check out my chain and guard etc. Thanks guys.
 
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