R1100S idles way too slow and tries to stall when hot - Why?

[montliz]

Hi all,

Something new with my '00 r1100s. I've only had this bike for less than a year, so I don't have a really long history with it. It has 24,000 miles and I've put maybe 1000 of them on it, my goal being to get it back in shape so I can go somewhere on it. I've installed the AF-XIED to relieve the surging and it's running great now; it's set at 8. The AF-XIED may be a red herring here but I mention it in the spirit of full disclosure.

I've set the valves and balanced the throttle bodies (500 miles ago) and the bike really hums out on the big road. Love riding it (if I'm going somewhere).

But I went out for a ride today on this sunny and beautiful 98F/95% humidity afternoon and when I came back into town the bike died at the first traffic light. It fired right back up and we headed to the house, but I noticed at the intersections that the idle speed had dropped to maybe 400 or 500 RPMs and the engine was trying hard to die at that speed.

Back in the garage, with my earplugs out, I hear a lot of, for want of a better word, "clanking" noise at this way-too-low idle speed. I attribute this to the rattling and banging of all the clutch and trans parts while the engine is struggling to stay lit. All I have to do to make this go away is to either put in the clutch or use the throttle to increase the engine speed to 1000 or so RPMs, which is where it should be idling anyway. I don't think this clanking is related to the too-slow idle. (Could be wrong - whaddya think?) Plus I love the way I can make it disappear when I want to. Call me crazy.

All the cable adjustors and the big brass screw settings, which I marked when I set them, are unchanged. The cable spools (is that the word I want?) are unencumbered and clean, and the throttle cables seem to be operating smoothly and evenly. The vacuum caps are still in place. The engine runs smooth and great at all speeds above 1000 RPMs.

What's going on here? Does this ring a bell with anyone? I'm so tempted to just increase the main throttle cable idle setting on the right side to make the noise stop and the idle go back up to 1000 RPMs where it's smooth but I know that ain't right and also doesn't address the problem. What to do?

As always, thanks for your advice.

Johnny

 

[m_stock10506]

Check to make sure your clutch is fully releasing when you pull in the lever. Do your throttle body sync again with the engine fully warmed up. Be sure the passages at the big brass screws are cleaned out.

 

[mneblett]

What to do?

Verifying -- this was a sudden problem noted when you came to the light, not something that might have been getting worse over time?

Easy stuff first -- my first step would be to note the position of the BBSs, then remove each of them and verify the bypass air port that allows air into the throttle bore (downstream of the throttle plate) is not blocked. Fuel and spark tests would follow once the bypass air is ruled out.

 

[mcrenshaw]

You have had the bike about a year, so during that time have you replaced the fuel filter? Almost sounds like the fuel pump is working OK, but is starving possibly due to a blockage in the fuel filter. Ethanol is a huge problem with the rubber parts in these bikes. If you've not replaced the fuel filter before now, it certainly wouldn't hurt to do so. While you are at it replace all of the internal lines in the tank as well as the external lines.

Another thought, while you have it in service wouldn't hurt to test the fuel injectors. They can also become clogged as a result of ethanol damaged rubber bits. Techron, Sea Foam, or a similar product is also good to keep injectors clean.

 

[mneblett]

You have had the bike about a year, so during that time have you replaced the fuel filter? Almost sounds like the fuel pump is working OK, but is starving possibly due to a blockage in the fuel filter. Ethanol is a huge problem with the rubber parts in these bikes. If you've not replaced the fuel filter before now, it certainly wouldn't hurt to do so. While you are at it replace all of the internal lines in the tank as well as the external lines.

Another thought, while you have it in service wouldn't hurt to test the fuel injectors. They can also become clogged as a result of ethanol damaged rubber bits. Techron, Sea Foam, or a similar product is also good to keep injectors clean.

While changing the fuel filter is good maintenance, the fact that the bike runs strong when over 1000 rpm suggests that fuel flow is ok. That's what pointed me toward the bypass air first.

 

[montliz]

Thanks all, great advice and good leads. I like the clogged low-speed air passages theory; that sounds right to me. I'm going to go in there first. This is new territory for me, but I bought the bike partly as a learning project, so this will be one more great opportunity for me. I haven't gone the extra mile and changed the fuel filter and lines, but I have had the tank off and drained twice so I've provided lots of opportunities for stray rubber bits to come loose and find their way to the throttle bodies. The fuel filter and internal hoses are now high on my list of things to do.

I'm thinking it's not the fuel filter or lines this time because it has plenty of fuel supply at highway speeds. It's only starving at idle, so I'll bet I find the problem inside the throttle bodies somewhere.

Mark, in answer to your question, this was a sudden problem that just came up at the end of my highway ride yesterday, but now that I think of it, the idle has been growing steadily less dependable for a while, so that points again to the clogged throttle body theory.

Michael, the clutch operation is good, so that's not going to be it, but thanks for the suggestion.

So, things to do - Thanks again and I'll let you know what I find.

Johnny

 

[pauls1150]

If you've set the valves to "factory spec", then they'll be tight when they are hot, and this will most definitely be detrimental to a steady idle. Intake spec is .006", so I always set mine to the sloppy side of .007". Exhaust spec is .012", so I set mine to .014". A bit noisier, but it works GREAT.

Low idle will seem to exacerbate clanking... but it's also worthwhile to upgrade your left-side cam chain tensioner to the newer type.

 

[roger 04 rt]

Your best bet, so you aren't guessing, is to borrow a GS-911 and log realtime data while the problem occurs. To me, based on all the symptoms you presented, it sounds as if either the throttle is closing while it idles, or the O2 sensor/AF-XIED pair is signaling lean at idle causing the short term trim to add too much fuel.

A weak O2, or a failed or defective AF-XIED could be causing the problem. BTW, the manufacturer had a batch of less than two dozen with a defect, see: http://forums.bmwmoa.org/showthread...d-O2-Sensors&p=1003678&viewfull=1#post1003678.

 

[montliz]

If you've set the valves to "factory spec", then they'll be tight when they are hot, and this will most definitely be detrimental to a steady idle. Intake spec is .006", so I always set mine to the sloppy side of .007". Exhaust spec is .012", so I set mine to .014". A bit noisier, but it works GREAT.

Low idle will seem to exacerbate clanking... but it's also worthwhile to upgrade your left-side cam chain tensioner to the newer type.

Thanks Paul,

I'm with you on the generous valve adjustment with extra comfort zone. The specs on mine are 15 and 30 and I set them so they would just barely, barely hold the feelers in place. I'd say they're defiinitely on the sloppy side and you can hear them all working in there. Plus I set them about 1000 miles ago and this idle problem is very recent and new. What I could see of the cam chains and tensioners when I was in there looked all beautiful and low-mileage, as did the valves and adjusters. My amateur stethoscope doesn't pick up any noise from the cam chains, though admittedly that's an imperfect science at best. Still I'll be looking for a good excuse to go back in there to recheck my work.

Johnny

 

[montliz]

Your best bet, so you aren't guessing, is to borrow a GS-911 and log realtime data while the problem occurs. To me, based on all the symptoms you presented, it sounds as if either the throttle is closing while it idles, or the O2 sensor/AF-XIED pair is signaling lean at idle causing the short term trim to add too much fuel.

A weak O2, or a failed or defective AF-XIED could be causing the problem. BTW, the manufacturer had a batch of less than two dozen with a defect, see: http://forums.bmwmoa.org/showthread...d-O2-Sensors&p=1003678&viewfull=1#post1003678.

Thanks Roger,

I hope I don't have to go into the electronics on it this time, but it's good to know that remedy is available. I'll see if I can find a mechanical failure first and then go there if I can't. When it tries to die it acts more like it's starving for air than like it's gotten too rich and is loading up. If you rev it up out of the superlow idle zone it comes right back to life and doesn't seem to have to overcome any fuel overloading.

If I were out on the road I could probably just run the throttle stop adjustment up enough to open the plates until I got a decent idle, but of course that would just alleviate the symptoms without addressing the actual problem, so I imagine that would be a short-term fix only.

Johnny

 

[dieselyoda]

Have you checked your air filter? How old are the plugs?

Maybe the perfect advice has been given but it all might be worthless if you haven't confirmed the basics.

 

[montliz]

Have you checked your air filter? How old are the plugs?

Maybe the perfect advice has been given but it all might be worthless if you haven't confirmed the basics.

Thanks Dieselyoda,

The plugs are new (500 miles or so) and I cleaned the air filter (K+N element) at the same time. It's clean now and wasn't particularly dirty before. Also at that time I adjusted the valves and synced the carbs. All those tweaks made a nice difference in performance and it's been running really well until yesterday with this idle problem.

Update: I just now took out the Big Brass Screws and they didn't look good at all. At first I thought the tapered tips were coated with black plastic, but it was just gunk. They even had little globs of the same black stuff stuck to them, like they had been dipped in it, and I know dat ain't right.

I haven't removed the tupperware or the airbox (yet), so I haven't been able to look down inside the throttle bodies, but what I can see down in the seats where the BBSs go is not pretty at all - definitely needs cleaning. I'm going to see if I can find any instructions on cleaning up the BBS seats and passageways without actually removing and disassembling the throttle bodies. I think that would be a good first step. Do you have any suggestions for how to proceed? I'm hesitant to blow a bunch of air down in there if there's a safer way to get the job done. Maybe a little Q-tip and solvent action.. It looks like it's all brass down in there but it's hard to tell 'cuz it's covered with something that looks like carbon but I suspect is actually disintegrated rubber. Yuk.

Interesting side note : The right BBS was set at 2 and 1/2 turns out and the left was at 1 and 1/3 turns. Whaa?

Johnny

 

[mneblett]

Do you have any suggestions for how to proceed? I'm hesitant to blow a bunch of air down in there if there's a safer way to get the job done. Maybe a little Q-tip and solvent action.. It looks like it's all brass down in there but it's hard to tell 'cuz it's covered with something that looks like carbon but I suspect is actually disintegrated rubber. Yuk.

A shot of carb cleaner to start dissolving the gunk, followed by carb cleaner-soaked Q-tips until they come out clean, followed by dry q-tips.

Interesting side note : The right BBS was set at 2 and 1/2 turns out and the left was at 1 and 1/3 turns. Whaa?

Perfectly consistent with an idle adjustment being done while at least one of the bypasses was gunky (technical term). If a pro did the sync, he/she should have noticed/flagged the mismatch as a problem.

 

[dieselyoda]

Swab them out is a good start but something that works and doesn't harm anything but is a pia to do, I spray CRC Throttle Body Kleen through the passage with the engine RUNNING.

I get a buddy, promise a cold bevy or three after, get him to start the bike, warm it up a bit, still running, pull the bbs, he stays on the throttle to keep it running and then I spray the stuff down the passages. After the horrific noise and smoke clears, we crack the tab on a little can of human lubricant, wait for the bike to cool and repeat.

In keeping that I think that whole world should adopt a beer as a unit of measurement for everything, the cost of the stuff is about two beers and you use about 1/4 of a beer per side.

 

[happy wanderer]

I don't like the idea of a K & N filter on a bike with such tight tolerances. They are fine on a race bike that you are going to rebuild often and clean after every race. On a street bike? No thanks.

You can get great quality replacement air filters that do a much better job of catching particulates from Beemer Boneyard or Electromotoelectrics for twelve bucks. Up here in Canada they are 30 or more at the dealer.
http://www.euromotoelectrics.com/Air-Filter-BMW-R-Oilhead-AF-528LX578-Mahle-p/af-528lx578.htm

 

[Omega Man]

In keeping that I think that whole world should adopt a beer as a unit of measurement for everything, the cost of the stuff is about two beers and you use about 1/4 of a beer per side.

From The Monkey Wrench Gang by Edward Abby-

"Time is relative, said Heraclitus a long time ago, and distance a function of velocity. Since the ultimate goal of transport technology is the annihilation of space, the compression of all Being into one pure point, it follows that six-packs help. Speed is the ultimate drug and rockets run on alcohol. Hayduke had formulated this theory all by himself." Chap. 2, p. 18"

OM

 

[montliz]

Swab them out is a good start but something that works and doesn't harm anything but is a pia to do, I spray CRC Throttle Body Kleen through the passage with the engine RUNNING.

I get a buddy, promise a cold bevy or three after, get him to start the bike, warm it up a bit, still running, pull the bbs, he stays on the throttle to keep it running and then I spray the stuff down the passages. After the horrific noise and smoke clears, we crack the tab on a little can of human lubricant, wait for the bike to cool and repeat.

In keeping that I think that whole world should adopt a beer as a unit of measurement for everything, the cost of the stuff is about two beers and you use about 1/4 of a beer per side.

Dieselyoda,

I wanna party in your garage!

I'm going to go ahead and hold off on spraying solvent into my 4000 rpm running bike in my 105f garage at the present time, but that is definitely going on my list of things to do if I want to spice things up a little. I did ask my wife if she wouldn't mind being my backup person on that job, but, sadly, she declined the offer. Some people just don't know how to have fun, I guess.

It's somewhat warmer around here than it is where you live, so we usually refer to honeydos and other home maintenance projects as three-beer or four-beer jobs, and I'm going to go ahead and classify your tune-up procedure as an excellent four-beer endevour.

Cheers, and keep up the good work!

Johnny

 

[rad]

I don't like the idea of a K & N filter on a bike with such tight tolerances. They are fine on a race bike that you are going to rebuild often and clean after every race. On a street bike? No thanks.

You can get great quality replacement air filters that do a much better job of catching particulates from Beemer Boneyard or Electromotoelectrics for twelve bucks. Up here in Canada they are 30 or more at the dealer.
http://www.euromotoelectrics.com/Air-Filter-BMW-R-Oilhead-AF-528LX578-Mahle-p/af-528lx578.htm

Gotta agree, nothing to gain, a lot to lose. Boxers do not suffer from low volume intake. Opening it up more with a K&N does nothing for performance. What it does do is filter out far less and put your engine more at risk.

Your S was surging? I have had a few oil heads and two S's, neither S surged. Could the unit you installed be masking another issue.

Could it be a failing stick coil? Not an uncommon occurrence in the oil head line.

 

[BC1100S]

Gotta agree, nothing to gain, a lot to lose. Boxers do not suffer from low volume intake. Opening it up more with a K&N does nothing for performance. What it does do is filter out far less and put your engine more at risk..

Sorry guys but I'm going to have to disagree with you. I've been using K&N air filters for about 20 years in all my bikes and cars with never an issue. Granted, I haven't gone 400,000 km in any of them but I did do 68,000 km on a Ducati 900 before I pulled it apart for some performance improvements (pistons, head work). Bike wasn't using any oil between changes at the time and the original cross hatch was on the cylinder walls.

A buddy of mine who has the identical bike to me (except for having the single plug version) was unhappy that in a roll on, I would pull ahead of him. He changed to a K&N filter AND a larger air intake tube and, in roll-ons, stayed even with me. I made a similar change and normal order was restored. . My feeling is the larger intake tube (without a pinched-down neck in it) made 90% of the difference.

Biggest issue with K&N filters is that people clean them too much.

YMMV

 

[rad]

Sorry guys but I'm going to have to disagree with you........

YMMV

Ya see, right there, that opening, ya lost me right there