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Discussion Starter #1
I have a 2005 LT with about 8.5K on it. I bought it used but the bike was very well kept. However I have noticed that while the bike drives perfectly, there is a rattling type noise at idle. It sounds like marbles rolling around in a tin can. When I pull in the clutch lever it is reduced by about 90%. Twisting the throttle also changes the noise. This is not a rhythmic frequency type noise like a lifter, but it is persistent growling. In the old days I would have said a throw out bearing was going bad. But I am not convinced that some other part is rattling and pulling in the clutch lever is just changing the load on whatever is loose.

Can anyone tell me if I should be worried and what may be causing this?
 

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BMW Guru
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The bike has a dry clutch. This is a normal noise. Don't worry about it.
 

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I've been told that it has something to do with the alternator drive. Throw on some power drain, like driving lights, and you'll hear it change again. Sounds awful, but I pay it no mind now.
 

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If it is the alternator klunk you're hearing, it should quiet down once it recharges the battery after the drain of the startup.
 

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I also have an 05. Mine makes the same noise but not all the time at idle. If you hear the noise, pull on the front brake. Does it get louder? If so I have been told it may be the alternator cush drive. It is annoying to me. I went for a 250 mile ride this weekend and the bike runs like a top. So I am not sure if I want to spend the money on a possible fix while the bike runs so good. My bike did not used to do this. I will keep an eye on your post to see what else you discover. I have not gone to the dealer yet because they are so far away. I am going there and have them listen to it and see what they think. I did speak with the dealer mechanic on the phone and he said he has seen them run 100k with the noise. Not sure if I believe him or not.
 

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Wrencher Extraordinaire
2005 K1200LT
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It is the "K Bike" Rattle and it is caused by these gears (a third one is hidden). Some rattle a lot, some are pretty quiet. One is on the crank, one is on the output shaft to the clutch (hidden) and one is on the alternator drive.

Marc, you can sort of see the cush drive at the front of the alternator.
 

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Discussion Starter #7
Are you all saying it can't be fixed or it isn't worth fixing?

You can tell that without the rattle the engine would be virtually silent. This rattle sure ruins the near perfect image the bike has. It is actually a little embarrassing. No one expects to hear such a noise form such a seemingly well designed bike.
 

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Well I have to say it took getting used to for me but it is no issue.

If you raise the idle by 200-300 RPM it should go away, mine does, and I never hear it riding.

That and the 4300 RPM or so K rattle motor buzz were about all that concerned me as a new owner noise wise. All motors have their noises and distinct sounds.

After reading about both here I have not given it a second thought.
 

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Wrencher Extraordinaire
2005 K1200LT
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tonygret said:
Are you all saying it can't be fixed or it isn't worth fixing?

You can tell that without the rattle the engine would be virtually silent. This rattle sure ruins the near perfect image the bike has. It is actually a little embarrassing. No one expects to hear such a noise form such a seemingly well designed bike.
Well I'll let you decide. It can be fixed but it would take replacing those pesky gears in sets until it was quieter. My cut on it is don't waste gas idling, just get going. Yeah, mine is really noisey too but I just keep the clutch in at the red lights anyway so I don't notice it too much any more. Just tell anyone that asks, they had to add the noise as too many riders kept trying to re-start the engine when it was already running.:p
 

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I forgot to remember the noise that all k bikes seem to make
sounds like gear lash to me , must be because when you get the drive train loaded up , you know in gear and moving it is gone

Bob G
99LT
 

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Could also be the plastic. Mine rattles at idle, but if I push or pull on the plastic up around the radiator it goes away. Some day I'll figure out which pieces are rubbing and put some foam rubber there.

-Scurrie
 

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I wear ear plugs and turn up the radio. No more odd noises.
 
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