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I just bought a K 1200lt last week with 29.000 miles. It is a very nice bike!
I rode last week around 300 miles with my lovely wife and we loved it. Now, there is only one thing that I am in doubt. The bike makes a nocking noise around 1000 rpm, and I took it back to the BMW dealer where I bought from , and they said it is normal. Would it really be normal for a BMW bike?
 

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Lotsa odd noises from these bikes, apparantly normal. Click on the 'similar threads' below for a few explanations.
 

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Yup, the altenator gears make a Whirly thump thump noise and the Fuel injectors a tick tick tick ..... It all is NO LONGER heard above idle speeds.
 

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Beginner said:
...The bike makes a nocking noise around 1000 rpm...
It's knocking to get your attention - it does not like to be at 1000 rpm, it would rather be at 3000-to 5000 rpm, or higher. :D
 

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Beginner said:
I just bought a K 1200lt last week with 29.000 miles. It is a very nice bike!
I rode last week around 300 miles with my lovely wife and we loved it. Now, there is only one thing that I am in doubt. The bike makes a nocking noise around 1000 rpm, and I took it back to the BMW dealer where I bought from , and they said it is normal. Would it really be normal for a BMW bike?
Every situation is different, but my first couple of trips on my new for me LT left me wondering what I bought into. For such a sophisticated machine, these things sure do make some different noises! I had a tinkle, (exhaust cover loose), a thumping (no idea, but the bike runs great), various squeaking while turning (fixed with a liberal use of WD40), ticking (I understand this is the fuel injection, not the valves like I thought), and a funny sound that comes from the clutch while putting it under a load that still worries me, but some 101,000 miles later it all works wonderfully, so I take it as the symphony of the ride, and enjoy every minute of it. For me, if it ain't broke, don't fix it. I think I would worry more if suddenly it all went silent....
Enjoy the ride!
 

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Wrencher Extraordinaire
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It is the K bike rattle and is caused by the gears seen here:
 

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Pull in the clutch lever and see if it goes away. Could be just some slop in the push rod.
 

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It is a characteristic of the dry clutch. My 02 didn't make as much noise as the current 05, but it is nothing to worry about.
 

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The one thing that will fix all of this is turning the stereo up louder.
 

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Tankist said:
I pull the clutch and it goes away.
Please tell me what it means.

Thanks,
Andrey
its the gears in the engine if the noise goes away when you pull in the clutch. There is a nice picture of the engine in someones post above.
 

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Speaking of noises, and this may be drive train rather than engine noise, my 2007 LT makes a clunk when engaging the clutch after rolling to a stop. I don't notice it when first starting out, but it occurs after that at every "rolling" stop where I disengage the clutch, roll to a stop or near stop and then engage the clutch again to pull away.

It feels like it is a roller clutch or something re-engaging. Does the LT have a torque-limiting clutch or some such in the drive train that would make such a noise?
 

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K bike rattle:
I posted about this years ago. Yeah, BMW mechanics just say "its normal". Well, it is, but that doesn't explain much.
Other's say it is the clutch, or alternator.
Excluding exhaust, plastic, and hosts of other sources of rattle, the K motor does (can) have an inherent rattle. The interesting thing is that it varies from bike to bike.
Here are some ways to test if your rattle is classic K-bike rattle:
1. Pull in the clutch: the rattle goes away. This doesn't mean that it is the clutch that is rattling.
2. Turn on a heavy electrical load like your driving lights: the rattle goes away. This doesn't mean that it is the alternator that is rattling.
3. If pulling in the clutch doesn't change the rattle, try this: put the bike in gear, hold the brake, and slip the clutch: the rattle goes away.

Look at the picture kindly posted above and reposted here with a photoshop added circles and arrows. Note that the crankshaft has a helical cut gear. The alternator shaft and the output shaft also have helical cut gears.

Here's the thing with helical cut gears: they create axial pressures on the shafts that they are attached to and the shafts that they drive. When the engine loads the alternator and output shafts the shafts will move a little in an axial direction. When there is no load on the drive train within the motor, the shafts can oscillate back and forth in an axial direction creating the rattle. Any shaft with a helical cut gear will do this. As soon as you load the drive train, the back and forth movement of the shafts will stop and the ratttle will stop. You can load the motor by turning on electrical stuff thus loading the alternator, the alternator drive shaft and the crankshaft, or by slipping the clutch thereby loading the output shaft and crankshaft.

The limit of axial movement in these shafts is determined by shims. There are maximum and minimum limits for movement specified in the BMW Service Manual. Some shafts will have more axial play than others. THIS is why some bikes have more K-bike rattle than others.

On my 2000 the crankshaft clearly is the source of rattle. I have listened with a mechanic's stethoscope with all the tupperware removed and it is clearing coming from the "bottom end".

In the attached picture, see the helical cut gears circled. The arrows show the direction of axial movement that the shafts may experience when there is no load on the bike and the shafts oscillate back and forth. Again, as soon as you put a load on the motor the oscillation stops and the rattle goes away.

It is a nice rattle, it can sound like rocks in a can, (remember the old trick of putting rocks inside someone's hubcap?), enjoy the K-bike rattle.... it adds character to the bike.

My bike rattled when new to the point of my distraction. Now at approx 60K miles it still rattles. Maybe it rattles less, or maybe I am just more used to it, who knows?
 

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My 2000 rattles too. It was something that bothered me at first but now I'm use to it I guess. It is so smooth above idle that I just ignore it. I did notice what I thought was a louder then remembered rattle so I reached down to feel and found the tupperware lower left front and the front peice below the radiator were chattering. They are not loose but just vibrating. I have not looked int a fix yet but maybe a rubber or foam spacer to tighten it up.
 

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I'm new as well, purchased an 05 with 32k mile, and some of the noises are driving me crazy. Last night I pulled the left panel off and found both studs missing from the front header pipe. It is obviously leaking. Im going to put new seals and studs through out. i'll let you know it that cures anything. Is the O2 sensor on this bike special or can i purchase one from autozone?
 

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dnifong said:
I'm new as well, purchased an 05 with 32k mile, and some of the noises are driving me crazy. Last night I pulled the left panel off and found both studs missing from the front header pipe. It is obviously leaking. Im going to put new seals and studs through out. i'll let you know it that cures anything. Is the O2 sensor on this bike special or can i purchase one from autozone?



Dnifong,
Wow! 2 missing? I have been told to check these because they have been known to come loose. I checked mine a while back and they were slightly loose.
 

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At the beginning I was also concerned about the engine noise knocking/rattle from my recently bought 99 LT with 23kmiles. Coming from 12 years of V4 Honda engines (VFR and Magna) the LT engine at first sounded pretty rough to say the least. Same feeling with the transmission which is noisier than on the Honda's. Somebody coming from riding Harleys may not have had the same feeling as I did. After 2 weeks of ownership and riding I now start getting used with the noisy engine. I read many things about the noise of BMW K engines, looked and listened at some videos of LTs on the web and came to the conclusion that there was nothing to worry about, it was just part of the charm of the LT. This K engine may be noisy but from everything I read it looks like it will easily reach 100k miles or more. I will still get my bike checked at the local BMW dealer for piece of mind :)
 
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