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markjenn 02-22-2006 07:58 PM

Retrofitting Late-Model Left-Side Cam Chain Tensioner
There has been some talk on this board and others about fitting the new-design left-side cam chain tensioner from the R1200 bikes to the oilheads. I just completed the mod on my 1999 so here's my report.

The advantage of the new design is mainly that you don't get the startup clatter that you get with the original tensioner as it pumps up with engine oil and starts doing its job. (The new tensioner reportedly retains oil pressure between startups.) Others who have done the mod also say the bike just seems to run better with the new tensioner. I was skeptical of this (and am always aware of how powerful the influence of suggestion is, especially after spending one's money on something) but I have to admit that my bike does seem to run noticeably smoother, at least at idle, with the new tensioner.

There are a couple long step-by-step treads over on on how to do it for the GS, but the most detailed one describes how to fit a "kit" that has now been obsoleted and also makes the job harder than it needs to be. But if you want to start at the beginning, here you go:

If you're doing an S, here's all you should need to know.

You need three parts to do the mod:

11317688629 - cylinder
11317656922 - piston
07119963308 - seal ring 18x22

These cost a reasonable $55 or so.

I also strongly encourage you to get a new o-ring that seals the intake side of the throttle body to the intake runner - it's not absolutely necessary, but the old o-ring has typically swelled and doesn't fit very tightly on the TB. So when you try and put the intake runner back on, it will tend to pinch and make this job a real bear. A new o-ring refits much more easily.

13541341797 - throttle body o-ring

This costs about $4.

Note that these parts replace the tensioner on the LHS only. The RHS tensioner appears to be unchanged on the new R1200GS and is not interchangeable with the left. So there are no retrofit options on the RHS. The LHS is usually the noisy one.

The thread above (and others) will tell you to remove electrical connectors, injectors, etc. but I found that I could get the TB out of the way by:

+ Removing the three hose clamps securing the TB (not sure you have to remove all three, but they're easy to get off and give the TB more "give" to help jockey it around).

+ Unbolt the intake manifold from the head (two allen bolts - a ball-end allen wrench helps on the top bolt).

+ Remove the two sheet metal screws fixing the intake runner to the airbox.

+ Push the intake runner off the TB and back into the airbox to free the TB.

Which gets you to this point:

Now simply bungee the TB out of the way, being reasonably cautious not to stress any of the fuel lines, electrical connections, or the throttle cable. There is plenty of slack and room so you don't need to go crazy here - just get it out of the way a bit.

The tensioner is just below the front telelever pivot at the base of the cylinder. The old one has a 17mm hex head and you'll need a 12-point box-end wrench to have enough swing room to loosen it.

When you pull the old tensioner body out, you'll find a long spring that goes between the tensioner body and a plunger down in the engine. Other threads have fashioned complex gizmos to get the spring out - I just shoved the body up under the telelever as far up and forward as possible, grabbed the spring with some needle-nose pliers, and yanked it out like a bad tooth. With the spring out of the way, you can get the tensioner body out, leaving the plunger inside the engine. I retrieved the plunger with a magnet, but you can fish it out with a variety of tools. Supposedly there is absolutely no worry of dropping anything down inside the engine.

Here's a comparison of the old tensioner and the new, the new one on the bottom:

Oil up the new plunger (which is spring-loaded inside) and stick it in the new body with the curved side out (where it will bear on the cam chain). At this point, it seems to help to put slack in the cam chain by bumping the engine forward in its natural direction of rotation - I did this by putting the bike in 6th gear and turning the rear wheel.

Put the new seal ring on the tensioner body, compress the plunger with your hand and you can fish the assembly into the cylinder. Once in, you have to push the tensioner body down against spring pressure while turning it enough to catch a thread. I was able to do this by hand with a few tries. Once it starts to thread, just torque it in. Getting a torque wrench on this baby isn't feasible, so I just torqued to feel. The new tensioner has a 15mm hex head, so you'll need a 12-pt 15mm box end wrench for tightening.

From this point, it's just a matter of getting the TB back on. Be careful of the o-ring on the intake runner side of the TB - check for pinching as you slide the runner on and use some kind of lubricant. Also note the alignment marks for making sure the intake runner is rotated correctly to align with the airbox and allow the two sheet metal screws to screw in.

Fire it up and enjoy a smoother and quieter engine.

- Mark

JonyRR 02-22-2006 08:36 PM

Thank you; how convienent, and a great tech report. I've had mine (and rapid's) in the shelf for the better part of a month (ordered from A&S) waiting for the copper washer: I had to call 'em 3 times; the last time fhey 'found' a couple on the parts shelf; supposedly they're in the mail and I can get this chore done myself.

Don Ro 02-22-2006 10:11 PM

Most excellent report, Mark.
And thanks for the reminder to order this kit along with the starter cover jumper post kit.
Chicago BMW, here I come.

dee jones 02-22-2006 11:15 PM

Thanks for the information and pics, certainly simplifies things having a visual.

Steve Carlton 02-23-2006 04:45 AM

Great post, Mark. Mine's actually being put in right now while my bike's in for a turn signal relay warranty replacement. I'll comment on how it runs in a day or two.

FastGaas 02-23-2006 11:58 AM

I did this mod about 3 weeks ago and it's great. IT was easy and took maybe 1 hr for me... and I was being careful. The sharing of information like this is truely the power of this BBS. Between this mod and the zero-zero FI adjustment my '99 went from a rough running bag of bolts to a sweet prrrrrrring cat.

Thanks to everyone that contributed

adrianw 02-23-2006 12:35 PM


I've thought about this a few times, the local wrench reckons I should leave things well alone....

I've 121,000 miles on he bike now, if I was to do this mod now, would it have an adverse affect on the rest of the mechanism if it found itself suddenly 'correctly' tensioned?

ie Seeing as play begets play, should I correct one aspect of it, or will this just upset the status quo?


ErricZ 02-23-2006 01:19 PM

Awesome! Now I have two new mods to work into my new (old) R11S!!!!! :D :D

markjenn 02-23-2006 02:13 PM


Originally posted by adrianw
I've 121,000 miles on he bike now, if I was to do this mod now, would it have an adverse affect on the rest of the mechanism if it found itself suddenly 'correctly' tensioned?
I doubt your cam chain cares or even knows what kind of doohickey is pushing on the other side, so I don't see a mechanism for screwing things up. Probably the biggest risk is that you stress old wiring or leave a vaccuum leak when you put the TB back on.

But... I'm a huge believer in "if if ain't broke...", so leaving it alone would be a good strategy. For the vast majority of bikes, the old tensioner did a fine job - there were a few exceptions where it stopped working or the clatter at startup was excessive, but they were outlyers.

- Mark

JonyRR 02-23-2006 02:33 PM

wow; 121K, eh. You should have some good ideas what consistutes a faliure after that kind of mileage. How about a thread on how long what lasted and what you had to repair...

repoe3 02-24-2006 03:26 AM

ordered the part to do the job. figure it cant hurt. needed some other misc. stuff too, so i saved with free shipping getting the other stuff.


Steve Carlton 02-24-2006 07:56 PM

Picked up my bike from the dealer today. $105 plus $5 tax for everything. Worth every penny to have it start up without the clacking! Can't say it idles or runs any different. Great mod!

Rapid Dog 03-05-2006 07:51 PM

...did miine this weekend...piece o is now clatterless at start-up...nice.:cool:

bikerfish1100 08-03-2006 11:56 AM

done. easy job. now it's quiet at start-up. yet to go for ride. (bumped so some of the newbies can consider this upgrade).

ErricZ 08-03-2006 12:02 PM

I did the LHS tensioner and now my RHS is making some noise. Now what?

(I also used the brute force method of removing the old spring and a magnet to remove the old plunger, much easier than the "instructions" purport it to be. :))

badger 08-03-2006 12:29 PM

Did mine a couple weeks ago. Startup rattle and the hot engine idle rattle are essentially gone. Very nice. Is there some kinda collection of the old tensioners--you know like sending them to starving Eithiopians who would be happy to have used, ineffective chain tensioners?

bikerfish1100 08-03-2006 12:57 PM

maybe the guys making Urals could use them. i'm sure that our old ones are still about 30 years ahead of their production designs.

Flatbutt1 08-03-2006 03:49 PM

for those yet to do this Eric used some sorta dental hook to get the spring out o my scooter.

Once again let me publicly acknowledge Eric's efforts on my behalf. He be a genuine bro!

bikerfish1100 08-03-2006 05:15 PM

i could see a surgical hook as being an easier tool than a needle nose. either way- it's a pretty simple job. mostly an issue of gaining clearance.

Rapid Dog 08-04-2006 08:38 AM

rh lh

I did the LHS tensioner and now my RHS is making some noise. Now what?
weird, same thing here, but I think it only happened once...guess I need to ride it more...anyone else's do the same?

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