Sound - Cam Chain Tensioner?

tom964 · 06:27 AM

Hi all,

I have a 1999 1100s I bought recently with about 40k on the odometer. I have been learning much from reading this board, including about the upgraded cam chain tensioner. I bought this bike from a dealer and do not know whether the upgrade was done, although I suspect not.

Is there a way to tell from the top of the bolt that is visible whether it is the new part? My research of pictures of the parts tells me the answer probably is no.

I'd appreciate it if someone listen to the referenced you tube video and tell me if the slapping/thumping sound is the chain and whether that means it likely could use the upgrade. The sound is most apparent when I move the camera down below and behind the left head, and then later when I slow the idle. As you'll notice, it can't really be heard on the right side.

MVI 2488 - YouTube

Thanks,
-Tom

wswartzwel · 10-12-2011, 09:41 AM

sounds like a worn throttle body to me. The throttle shaft doesn't fit tight in the housing and makes noise.

wswartzwel · 10-12-2011, 09:42 AM

Reach down where the cable attaches and push on it and see if it goes away.

tom964 · 10-12-2011, 10:13 AM

OK, I think you are right. When I went out and restarted it, it actually was not making the sound, but touching the left TB cam where the cable joins restarted the noise and I can make it come and go at that point. I tried the right side and it produced only the slightest feeling of thumping and little sound. The left is where it is really happening.

So I guess I have to do some searches on that now, unless someone wants to tell me if there is an accepted solution.

BTW, the video is from cold start up, so on the original point, was there anything in there that would cause you to think about the chain tensioner if you were me? Do it anyway as a precaution?

Thanks for the quick (and accurate) responses!

-Tom

RBMann · 10-12-2011, 10:15 AM

I am with wswartzwel on this one. Also you should notice the sound/noise change as you lightly bring it off idle, caused by the change in tension on the throttle shaft. Talking about a warm engine with the fast idle leveler in the off position.

wswartzwel · 10-12-2011, 10:17 AM

cam tensioner is a loud clack clack for about 2 to 3 seconds... Mine has been doing it for years... I have the new tensioner but am in no hurry.

There is a thread rbmann did on fixing throttle bodies with the kit available not through BMW but through the TB manufacturer.

tom964 · 10-12-2011, 10:25 AM

Quote:

Originally Posted by RBMann

I am with wswartzwel on this one. Also you should notice the sound/noise change as you lightly bring it off idle, caused by the change in tension on the throttle shaft. Talking about a warm engine with the fast idle leveler in the off position.

Yes I noticed the change with the change in tension. Seems kind of low mileage for such a problem. It is obviously a 12 year old bike, but it would seem this would be more use than time related.

tjs · 10-12-2011, 10:46 AM

www.bingcarburator.com shows a nice pdf. on TB shaft wear. they also sell rebuild kits. Not cheap but less than a new one. tjs

RBMann · 10-12-2011, 11:02 AM

Here you go-

Throttle Body rebuild

tom964 · 10-12-2011, 11:21 AM

Thanks again. This is great info. Not that I am happy to have to think about rebuilding a throttle body. I was much more at ease thinking maybe all I had to do was change out the chain tensioner.

I called Bing and they would also do the rebuild themselves, for $$. So I'll be reading up on these threads and seeing if I want to tackle it myself, send it in to Bing, or find a local guru. I have the carbs on my 89 TransAlp off for a rebuild, maybe that will give me the confidence for this job, or the lesson that I shouldn't even try.

I had already planned on replacing the entire cable/bowden system, just on the basis of age.

Noblehops · 12:53 PM

Quote:

Originally Posted by wswartzwel

sounds like a worn throttle body to me. The throttle shaft doesn't fit tight in the housing and makes noise.

OK Bill that was pretty boss. Nicely done.

Re the tensioner, the original tensioner has a 17mm head and the replacement part a 15mm head, and so that's the quick way to see if yours has been previously updated.

N.

P.S. Nice writeup on ADV with some alternatives and wisdom:

http://advwisdom.hogranch.com/Wisdom/CamChainTensionerSwap.html on the process:

wswartzwel · 10-12-2011, 01:50 PM

No..no no... don't send people down the road packing... We have the definitive thread here in house.

Retrofitting Late-Model Left-Side Cam Chain Tensioner