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Thread: 1999 R1100RT Inconsistent Idle speed....sometime dies at the Stoplight.

  1. #16
    MOA #24991 Pauls1150's Avatar
    Join Date
    Apr 2008
    south of Los Angeles
    Aftermarket exhausts for an RT are pretty rare; Staintune used to have one but it's NLA. Be advised that most of the restriction and sound reduction is in the catalytic converter; that's also where a too-rich fuel mix would clog things up.

    (Side note: I'm in CA... While the present law clearly states that the exhaust system must have the EPA approval pressed in to it, no police officer would bother anybody whose bike is not "offensive", as long as no other criminal activity is involved - they have better things to do.)

    There are maybe 8 (?) different CAT-Code plugs of different colors; they are available at your friendly local dealer. There's a list somewhere of which plug is intended for which bike, but I can't find it now, dang it.

    Yes, over-thinking... The computer adapts its fueling map over time, and it has "rough" settings and "fine tuning" that all get tweaked. If you want to re-set the Motronic, it's easier to pull fuse #5 (guys - is this correct for a '99?) for AT LEAST ten minutes than to disconnect the battery.

  2. #17
    Registered User
    Join Date
    Mar 2012
    Kansas City, MO
    Well......I guess that I'm just about ready to call this done. Here's what I know:

    I took it out yesterday afternoon for a hard test ride. During that time I did quite a few of those "throttle chops" where I accelerate hard at highway speeds, quickly cut the throttle and pull in the clutch. The result was that yes, the rpm would dip down to 700-800 or so. A couple of times it would even stall. I parked it at the grocery store for about 10-15 minutes and came back out and started it up. It idled at about 1500rpm. At this point I'm confused and disillusioned.

    This morning I decided to remove fuse #5 for about 15 minutes and let the Motronics reset itself. I then took it out for a normal, sensible ride; no throttle chops, no abrupt inputs. After the engine temp got to 5 bars it would idle normally at about 1200 rpm. I actually went for 2 rides, a 30 mile country/2 lane ride and a 35 miles high speed interstate ride. On both rides I rode normally with normal acceleration and stops. The result was that during this normal operation, on stops, the rpm might SOMETIMES dip a little to just under 1000rpm but it returns to 1200 within 3-4 seconds. I cannot tell you if this means that the problem is "fixed"....but to me it is something I can live with.

    Also I wanted to check the fuel mileage since one of the stated problems that might occur from not having the cat coding plug installed was reduced mpg. It appears to get around 42mpg...that is WELL within acceptable limits.

    Thank you everyone for all the good advice. I'll keep you posted if anything changes.

  3. #18
    Registered User bewareboy's Avatar
    Join Date
    Sep 2015
    Cincinnati, OH
    Quote Originally Posted by Pauls1150 View Post
    The BBSs control only the air at idle, since the computer is responsible for adjusting the actual mixture (by controlling the length of time that the injectors are open). Backing them out allows more airflow (up until maybe 5 or 6 turns out, after which it becomes useless).

    When the throttle stops are properly set, there is only a tiny margin of butterfly opening at idle; you can see this if you look down into the throttle body. It's also important that the butterfly itself is mounted properly, but that's another thread...
    Complete instructions for adjusting the entire setup can be viewed by Advanced-seaching this forum specifically in the Oilheads section and look for posts by Roger04RT; he's done some great stuff. More info can also be found on the Internet BMW Riders site but this is "older" information and won't exactly match what Roger has written up. He's also done a write-up on the cat-code plugs; which plug is installed depends on not only which engine, but which country and what intake and exhaust setup it has. Removing the plug completely may help at certain RPM, but will be detrimental at other RPM, as it affects the computer's "adaptability".

    I agreed that the [silly] charcoal canister should be deleted completely, and the vacuum ports on the throttle bodies must be securely capped off - any air entering thru there is completely unfiltered, and will also affect your sync efforts.

    Not to hijack the thread, but I would be interested in your comment about properly mounted butterfly plates. I rebuilt my 2004 throttle bodies a few years ago and on the first unit I did not pay too close of attention to the orientation of how it came out nor went back in. On the second unit I was more conscientious to reinstall it in the same orientation as it come out. Not sure if the plate has ever so slightly beveled edges, top or bottom, frontside and backside? I did use feeler gages to get the slight gap equal all around. I did a simple and quick search on the forum and did not find anything that discussed the throttle body butterfly plate installation.

    Jim "BewareBoy" Snyder
    Cincinnati, OH
    2004 R1150RT

  4. #19
    MOA #24991 Pauls1150's Avatar
    Join Date
    Apr 2008
    south of Los Angeles
    If these are the ones that you recently posted pictures of in another thread (before & after cleaning), looks like you got it right. It is possible to mount them and not have the plates plus screws centered in the bore.

    If you back off the throttle stop screw and see that the plate is sitting concentric in the bore, that's good;
    If you set/sync the screw and cables so that you see a very slim, smooth and even arc around the perimeter, that's also good.

    Back around July of 2018, BeemerMyke had a worn butterfly to replace.

    I don't know if they're beveled, or have a front and back, or a top and bottom ... Anybody?

    BTW, in the airheads' Bing carbs, those actually do have a "shape" that must be adhered to when installing.

    > PM sent.

  5. #20
    Pepperfool GSAddict's Avatar
    Join Date
    Feb 2008
    Sechelt, British Columbia
    Google Dan Cata.
    He supplies the throttle shaft kits.
    He has a comprehensive how to procedure available.
    Correct alignment in the bore is critical
    This vid is also helpful

    Roger 04RT has the calibrating procedure for the TPS.

    Butterfly is not beveled
    Ufda happens..........

    Need your R11xx Hall sensor rewired? PM me.

  6. #21
    Registered User
    Join Date
    Mar 2012
    Kansas City, MO


    Took the bike on an 800 mile ride through the Ozarks. This is what happened:

    Left the KC metro area at around 9am. At my first stoplight the bike wasn't warmed up yet. However it developed a misfire reminiscent of a coil dropping out....or a spark plug cap not secured. This would occur briefly and quickly return to normal idle. When I got it out on the interstate it ran fine at normal cruising rpm. So...a few times I would drop the throttle, pull in the clutch to see what it would do...same thing, something like a misfire, once it even died. After about 12 miles of interstate riding I figured it was warmed up so I pulled off and listened to it idle. No problems. I continued on my trip. That misfire never happened again.

    The bike performed well. The only 2 complaints are that I'm not used to the higher idle speed, it idles at about 1250-1300rpm. Also at very, very small throttle apertures at highway speed I get a slight sensation of surging. It is difficult to tell if this is a genuine engine/fueling problem or wind buffeting (this is the first time I've had it on this long of a trip). Overall I would rate it's drivability and performance at 99%. 43MPG.

    I checked out the Euromotoelectrik site....they have what they call a "fuel injector upgrade set" for $180 or so. That's almost cheap enough to role the dice on. Hmmmm.....

  7. #22
    Registered User dieselyoda's Avatar
    Join Date
    Mar 2013
    Winnipeg, MB, Canada
    I still have the opinion you have a air leak.
    1997 R1100RT, 1981 KZ 440 LTD, R80RT, R90/6 sidecar, K1100RS,1983 K100RS (Cafe now)

    “The major civilizing force in the world is not religion, it is sex.”

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