1150gs TPS set and throttle stops

Discussion in 'GS Boxers' started by Iplayforme, Jun 12, 2018.

  1. Iplayforme

    Iplayforme Adventurer

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    hello

    I'm trying to tune my 1150gs as finely as possible. I have a twinmax and a gs911 on the way.

    I have concerns because my idle is too high and my brass screws are not equal. Even with slack cables. So I seem to think I need to adjust the throttle stop screws. however it seems like such sacrelidge. I'd think that with the gs911 and twinmax I should be able to adjust anything. I'm unable to distill a procedure from my readings here. there is a lot of content, but there's some disagreement and a bunch of technical discussion that goes way beyond. it's also been a while since this has been a hot topic.

    is there an accepted procedure that's been settled on that can fix my idle and ensure my tps is set. including adjusting the throttle stops. based on my blue paint it seems the tps has been touched
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  2. Jim H

    Jim H Been here awhile

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  3. pharme

    pharme Been here awhile

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    Yes, i have followed this thread to achieve with success of what OP has described of the throttle stop screw. Also about high idling, if it's at operating temperature only (5bars) then it could be the butterfly plates are not properly aligned in the TBs. It happened to mine before.
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  4. Jim H

    Jim H Been here awhile

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    Iplayforme - if idle is too high there are causes unrelated to throttle stop screws. In fact, if your throttle body stop screws are still marked with blue torque paint, I recommend checking all other potential causes of higher than normal idle rpm first, particularly since normal minor wear at the stop screw contact point will decrease butterfly angle slightly and lower idle rpm, not increase it.

    Higher than normal idle rpm is more often caused by vacuum leaks in the intake path and there are a few common leak points. For instance, if still fitted, check the vacuum hoses connected at a nipple at the bottom forward end of each throttle body tube. If your bike has had a canisterectomy, these hoses have likely been removed and replaced with rubber caps. These hoses (or caps, if fitted in lieu of hoses) will age with time and heat and are the most common source of vacuum leaks. Second common cause is loose hose clamp or cracks in the "intake manifold", which is the rubber tube connection between the front of the throttle body and the engine head intake port. If your bike will start and idle, you can spray possible vacuum leak areas with something like brake cleaner to see if idle rpm changes.

    To begin troubleshooting, how far open are each BBS? If you haven't already checked, slowly close each in turn and count rotations until the BBS just seats, then record the turn count for each side and restore original position. Depending on current position, idle can be slowed by using these screws to decrease intake air.

    There are more things to check after you post results of the above troubleshooting.

    Again, I suggest developing a troubleshooting plan to check for and eliminate the more common causes of higher than normal idle rpm.
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  5. Iplayforme

    Iplayforme Adventurer

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    Jim

    I'm going to follow your suggestions and report back. I'm sure the boot/manifolds are ok. I checked them already. I did remove the canister but the vacuum lines are still there. I vaguely remember leaving them for some reason. That will be my first place to look. The BBS's are at 2 turns and 1.5 turns out. I think I remember trying to bring the idle down with them and struck out. Again, I'll report back ASAP.

    Thank you
    #5
  6. Jim Moore

    Jim Moore The Real Deal

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    What is the idle now?

    Btw, a half-turn difference in the BBSs is no big deal.
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  7. Iplayforme

    Iplayforme Adventurer

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    idle now, if the tach is 100% accurate. is 1300 to 1400.
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  8. Jim H

    Jim H Been here awhile

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    Some initial troubleshooting questions:
    1. Has idle always been fast since you acquired this bike? If not, was the increased idle rpm sudden onset or has it gradually increased? If sudden, what was the last thing you did on the bike before idle rpm increased? If it was removing the canister, that pretty much narrows it down.
    2. If vacuum hoses are still connected to throttle bodies, what are the other ends connected to? I recommend they be replaced with rubber caps that you can easily confirm are installed and intact. BMW sells these caps but they can also be found at McMaster Carr or some good hardware stores.
    3. When you earlier said idle was too fast even with slack in cables, did you also slack the fast idle cable at the left handlebar grip? If not, that component may be where to look.
    4. Have you checked for small stones or other debris residing in the valley of the throttle body pulleys under the throttle cables?
    5. With slack in the throttle body cables, when you manually turn the butterfly pulley toward open and release, does the pulley snap back to the mechanical stop screw?
    6. When you try to wiggle the pulleys tangent to the shaft is there noticeable radial "play" between throttle shafts and their bore in the throttle body?
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  9. Jim Moore

    Jim Moore The Real Deal

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    Have you tried turning your brass screws to the right to lower the idle?
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  10. Iplayforme

    Iplayforme Adventurer

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    I had limited time today, but since my gs911 came in the mail i had to play with it. After setting it up i plugged it in to find the TPS angle at .64. I gather it should be .32. I made the adjustment and it seems to have brought the idle down to spec. Almost. It goes between 1150 and 1200. I'll work on that. But maybe it's gonna be just that easy.

    I'll probably have a story to tell tomorrow or Saturday depending on when I can get a few hours with it. Looking good though.
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  11. Steptoe

    Steptoe steptoe

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    It's not rocket science, it's a BMW twin - Just turn the idle screws (BBS) in half a turn each until you get the idle you want... Do not touch the throttle stop screws, there is no need.
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  12. Iplayforme

    Iplayforme Adventurer

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    it might not be rocket science but it's even more complicated than that if you don't know what the last guy did. it wasn't always my rocket.

    no this morning it wants to idle at 1300 1350 again I'm fiddling with it now
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  13. Iplayforme

    Iplayforme Adventurer

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    I just want to offer a summary response to the ideas that others have put out. and thank you all.

    Bike is a 2003 1150gs with 27k on the odometer
    All slack is out. fast idle as well
    no stones in pulleys
    no weak springs or hangups. plates make a solid return to the stops.
    not any play in the throttles that I can detect, however, if I press the throttle wheel firmly on to the stop with my finger there is a ticking that disappears. suggesting that there is either some play somewhere or the plates are flapping a bit.

    no leaks around the boots

    and no major changes brought this on but I did put rubber caps on the TB nipples

    I think that covers it.

    I managed to get to 1100 at .5 turns out. is that a problem.

    I'm going to go take a test ride.
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  14. Jim H

    Jim H Been here awhile

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    1/2 turn out on BBS is not a problem.
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  15. Jim H

    Jim H Been here awhile

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    If you've ruled out vacuum leaks, other than TPS adjustment slightly off, another possible cause of higher than normal idle speed is sticking throttle cables or gummed up Bowden box pulley.
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  16. Xyphon112

    Xyphon112 Been here awhile

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    If this hasn't been mentioned I would also check the O rings on the intake tubes leading to the TBs. They get worn out and can cause vacuum problems as well.
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  17. Trevor Hallam

    Trevor Hallam n00b

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    If you've got ticking that goes away when you touch the TB cable pulley, there is likely some play in the TB shaft that shouldn't be there. It could be sucking air through there, same issue that Xyphon112 mentioned.

    Just rebuilt the throttle bodies on my R1100GS and spent a lot of time getting it just right after, including adjusting the sacred throttle stop screws (GASP!). I got a rebuild kit from Dan Cata through Beemer Boneyard. Ticking is gone, and consistent tuning was much easier to achieve.

    I wouldn't bother fiddling with the BBSs until you have your tiwnmax or other monometer hooked up. I made one from a board, some tube, and some two stroke oil. Correct idle speed is worthless if the cylinders are brought out of balance to achieve it. You may idle at the right RPM, but everything after that will feel like hell. When I bought mine used, the first thing I did was synch the throttle bodies and it felt like I'd dropped a brand new motor into it.

    Always worth taking out the BBSs to have a look at them too. Mine had built up deposits on the tapered portion, and this would have certainly caused them to flow differently from each other at the same adjustment. There's no sense in trying to tune everything to perfection without making sure you're working with clean components.

    I did the Zero=250 procedure (what I think was the final evolution of the zero=zero procedure for setting the TPS) as well and it runs like a top. Check out the posts from roger 04 rt on this.

    The IBMWR and Oilhead Riders "Oilhead Mainenance" document is well worth printing for the shop too if you haven't already.

    Good luck.
    #17
  18. Iplayforme

    Iplayforme Adventurer

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    I may just do the rebuild at some point. I might learn the hard way, but I'm not going to let the stop screws too bad. I have a twinmax and if it will balance with adjusting the cables it BBS than the same has to be possible with the stops. roger 04rt seems to have the definitive procedure for this.

    I did today achieve 1150 rpm idle, balance at idle and higher. I took a ride and then idle went to 1250 1300. I'm happy with everything on the road though. something just must be a bit off. the PO seemed to have taken good care of it, but it is 15 years old now.
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  19. Jim H

    Jim H Been here awhile

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    Idle rpm increase like this after throttle use as on your ride after setting the 1150 rpm idle sounds to me like sticking throttle cables or sticking butterfly/shaft(s). Suggest confirming throttle pulleys are free to return to the stops next time this happens. With engine off, manually rotate the throttle cable pulleys, one by one toward the open position by about 20deg and release. You should hear a clack when the pulley stop hits the stop screw. If it does, the shafts and butterfly position on the shafts are likely OK and cable slack is adequate. To check for freely moving cables you can operate the handlebar throttle with the engine off to 1/4 throttle and slowly return to closed position. Then manually rotate the pulley in the closed direction one side or other first, then repeat the "open to 1/4 throttle and slowly close" for other side. If one or the other pulley is not on the stop when you manually move pulley closed, you've identified the problem. You can reach the pulleys to do these manual checks by extending your open under the throttle bodies to be able to rotate the pulley with your fingers. There's a small nub at the fwd bottom of each pulley that helps to rotate pulleys manually. If these checks don't indicate any repeatable problems, further troubleshooting will be next.
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  20. Jim Moore

    Jim Moore The Real Deal

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    If the O2 sensor is unplugged the idle will vary as the engine gets hot. People unplug the O2 sensor on those bikes occasionally to eliminate surging.
    #20