My K1100RS pulls off at the lights like a tractor engine

[JonnyB]

Wondered if anyone can tell me if this sounds normal or not. My K1100RS sounds like a tractor engine accelerating at low revs. When pulling away in 1st gear there is a distinct low pitch grunting sound. If I use more revs when releasing the clutch I don't hear it and as soon as I'm away from Idle revs >1500rpm it's silky smooth. I'm wondering if it's valve clearances might need adjusting, or whether being a 4 cylinder it just doesn't like pulling away at very low revs. I'm used to riding a Yam MT-03  660cc single and that flies away at low revs so maybe it's just me. It's new to me at 66k miles and I don't know anything of it's recent service history.

Thanks in advance.

Jonny

[Laitch]

Wondered if anyone can tell me if this sounds normal or not. If I use more revs when releasing the clutch I don't hear it and as soon as I'm away from Idle revs >1500rpm it's silky smooth.
. . . it just doesn't like pulling away at very low revs.

It sounds normal to me. They make noise when they're lugged in any gear.

[JonnyB]

Ah right thanks, so it's fairly normal then. Will just give it a few more revs when pulling away.

[Filmcamera]

That is what I do, just think of the tractor noise like an aircraft stall warning buzzer..

[alexis291]

There was a post on here a while ago asking for the solution to the "pencil on a biscuit tin" noise. Mine does it too. I've searched for loose bits but never found any.


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[JonnyB]

Yes pencil on a biscuit tin. That's a good analogy.

[Laitch]

There was a post on here a while ago asking for the solution to the "pencil on a biscuit tin" noise.

Yes pencil on a biscuit tin. That's a good analogy.

Is that a pencil with a sharpened tip tapping on the biscuit tin cover, or its eraser doing the tapping? Has the tin been emptied of biscuits? Is it the sound of the pencil rolling along the surface of the biscuit tin? Is this a #2 pencil under discussion?

[JonnyB]

The main points are that it must be of rounded hexagonal cross section, wooden construction with graphite core, preferably on the H side of the hardness scale for higher efficiency of sound transmission down the core. Less biscuits are preferable to increase the tin cavity volume and allow for unabated reverberation with side walls and base. This is convenient as the average K rider will have already eaten them before attempting the experiment. Then throw away all evidence of the experiment before the wife realises that you are a strange individual and probably need psychological counseling.

[rbm]

Is that a pencil with a sharpened tip tapping on the biscuit tin cover, or its eraser doing the tapping? Has the tin been emptied of biscuits? Is it the sound of the pencil rolling along the surface of the biscuit tin? Is this a #2 pencil under discussion?

Laitch, you're such a shit disturber. :hehehe

The poor guy's only got 20 posts. :nono  Wait until at least 25. 

[Chaos]

mine sounds more like a crumpet tin.  should I be alarmed?

[alexis291]

I really don't think y'all are taking this seriously enough.


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[alexis291]

[emoji57]


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[rbm]

I think the consensus from this thread was that the noise you're hearing is related to lugging the engine.  I personally have never heard such a noise from any of the K-bikes I've owned so I can't offer any advice as to the source of such a sound as I have no personal offer experience.  Is the noise present when in neutral on the centre stand (stationary) or when in gear and in motion (mobile)?

[JonnyB]

It’s only when pulling at low revs. I seem to be the only guy driving one of these around central London and with all the luggage on but it’s also a great commuter especially in cold winter, but that means I am constantly at the lights or in traffic so frequently stopping and pulling away at low revs and it grunts/chatters if it don’t give it a good blip before letting out the clutch. Idling is great as is driving at higher revs. It’s definitely not the clutch which works great.

[Laitch]

It’s only when pulling at low revs. . . . at low revs and it grunts/chatters

You'll get the hang of it and you'll quiet it down.

[The Mighty Gryphon]

I am going to guess that the noise is the result of lash in the crank to output shaft gears.  There is an anti-lash on the output shaft with a spring that has been known to wear.  While it sounds like crap, it doesn't seem to cause any serious problems. 

[JonnyB]

A late thanks, maybe when. I give the bike a full service I’ll ask the mechanic to have a look at the transmission. Perhaps a worn bearing, or this anti-lash... i’ll have to look it up.
All the best. J

[BlitzenGruv]

Wondered if anyone can tell me if this sounds normal or not. My K1100RS sounds like a tractor engine accelerating at low revs. When pulling away in 1st gear there is a distinct low pitch grunting sound.

Sounds normal for a Harley, or a tractor. Anything else needs more revs before letting out the clutch.

[Andy FitzGibbon]

I am going to guess that the noise is the result of lash in the crank to output shaft gears.  There is an anti-lash on the output shaft with a spring that has been known to wear.  While it sounds like crap, it doesn't seem to cause any serious problems.

I second this. The noise may also be audible when "cruising" with little throttle, ie. mostly unloaded drivetrain. It's a well documented problem. Folks who claim that it's "normal for a K bike" probably just don't want to deal with the hassle of pulling the bike halfway apart to replace the anti-backlash spring.


Andy

[Laitch]

Folks who claim that it's "normal for a K bike" probably just don't want to deal with the hassle of pulling the bike halfway apart to replace the anti-backlash spring.

Did you deal with that noise in your bike, Andy, or was it something other than the anti-backlash system?  Maybe two different noises are being described.

[Andy FitzGibbon]

Did you deal with that noise in your bike, Andy, or was it something other than the anti-backlash system?

Currently dealing with it.  The spring was worn/stretched out, and the pegs it hooks to on the gear were worn as well, which allowed the gear teeth to line up with each other (ie. not do it's job).  I sourced an updated 12-rivet output shaft (includes a more robust gear/spring setup) that is currently waiting for me to install it. 

Maybe two different noises are being described.

Quite possible, which is why I seconded a guess, made by Gryphon.

Andy

[Laitch]

Currently dealing with it. 

It would be helpful for others if you document your work on that part with photos. They could supplement Bert Vogel's photos in his K100 essay.

[Andy FitzGibbon]

It would be helpful for others if you document your work on that part with photos. They could supplement Bert Vogel's photos in his K100 essay.

The job has already been well documented.  BMW themselves did a great job describing it here: [size=78%]http://www.bmw-k100rt-page.eu/manual/Engine/examinationEngine_24.htm[/size]


Bert's photos are already quite good, and show exactly the problem I'm describing- any photos I could contribute would be redundant.




Andy

[Laitch]

. . . any photos I could contribute would be redundant.

Nothing wrong with redundancy. Some instrux are easier to find than others.

Good luck.

[JonnyB]

Thanks for all the advise. I am using the bike as my daily commuter so I will have to find a time to get the bik apart at some stage; looks like a big job. So is it likely just the spring that needs replacing? I would like to prepurchase the likely components that will need replacing so I can rebuild in one sitting - I tend to fordet how things go back together otherwise!