weird stalling, hesitation

Discussion in 'Old's Cool' started by camgregus, Feb 13, 2011.

  1. camgregus

    camgregus riding gently now

    Joined:
    Feb 24, 2006
    Oddometer:
    3,014
    Location:
    on the banks of the mighty mississippi, AR side
    My 1989 R100 GS is doing crazy stuff again. It runs and starts fine. After a couple of miles or so, it starts hesitating on acceleration in second and third gear. Stumbles like it is about to stall.

    I just replaced the diode board. New ICU last year. All connections are clean and renewed. Floats show the same amount of gas. Petcocks flow well. I drained all the old gas out and put new in (it was only two or three months old....) I love my bike, but I'm just getting sick of it not treating me well enough to get it warm enough to tune....
    #1
  2. The Raven

    The Raven Banned

    Joined:
    Mar 19, 2006
    Oddometer:
    4,811
    Location:
    Off the map,
    Check your tank vent
    #2
  3. boxerboy81

    boxerboy81 Stay Horizontal

    Joined:
    Jul 22, 2009
    Oddometer:
    2,745
    Location:
    Melbourne, Oz
    Check the main jets for blockage.


    ..
    #3
  4. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    2,508
    This sounds like classic bean-can failure to me.
    #4
  5. datchew

    datchew Don't buy from Brad

    Joined:
    Aug 1, 2005
    Oddometer:
    7,409
    Location:
    Remember the Alamo!
    +1
    #5
  6. boxerboy81

    boxerboy81 Stay Horizontal

    Joined:
    Jul 22, 2009
    Oddometer:
    2,745
    Location:
    Melbourne, Oz

    +2 ...could well be, but I'd check simple things first.
    #6
  7. CurlyMike

    CurlyMike Formerly SaddleSoar

    Joined:
    Feb 4, 2008
    Oddometer:
    1,010
    Location:
    east of Dallas
    +3, thats the first thing I thought of when I read the title...

    I replaced mine with the electronic version from Rick at Motorrad Elektrik, have had no issues with the new upgrade. Yet to be seen if it will last 30 years like the last one.:ricky
    #7
  8. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    7,726
    Location:
    Atlanta
    +3. Sounds like what happened to me when mine died.
    #8
  9. Stagehand

    Stagehand Imperfectionist

    Joined:
    Oct 6, 2004
    Oddometer:
    27,363
    Location:
    Shawangunks
    Hey if you need a known working beancan for test I do believe I have one I could ship to you.
    #9
  10. camgregus

    camgregus riding gently now

    Joined:
    Feb 24, 2006
    Oddometer:
    3,014
    Location:
    on the banks of the mighty mississippi, AR side
    I could use a known working beancan. I don't think it is a fuel issue. It seems electrical.. I relubed my beancan year before last and it got better.
    #10
  11. DaveBall

    DaveBall Long timer

    Joined:
    Sep 30, 2009
    Oddometer:
    1,163
    Location:
    Vancouver Island
    Had similar issue a few years back. Replaced springs on mechanical advance as old ones had lost their tension. Lubed the pivot points and problem gone.

    A whole lot cheaper to throw in a set of advance springs and lube the pivots than replacing the whole can. Total cost to replace, including the delivery by mail from closest dealer - less than $5.00.
    #11
  12. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    I have had bean cans act like that. Spark plug caps. Coil wires shorting at certain vibrations. Carb enricher body gaskets. Coils. It could be about anything.

    Remember that aftermarket bean cans uses the exact same hall effect sensor that fails in the bean cans. The mechanical advance in the the bean can rarely acts up. When it does, it will slow acceleration and/or deceleration. It won't cause cutting out. It can't. It's mechanical, not electronic.

    If they only made an electronic advance for points! Then we could truly have the worst of two worlds! :rofl Kind of like the cable operated hydraulic brake!
    #12
  13. camgregus

    camgregus riding gently now

    Joined:
    Feb 24, 2006
    Oddometer:
    3,014
    Location:
    on the banks of the mighty mississippi, AR side
    plug wires and caps are good. Later black coil....

    Dragons.....
    #13
  14. The Raven

    The Raven Banned

    Joined:
    Mar 19, 2006
    Oddometer:
    4,811
    Location:
    Off the map,
    Might be time to go to points :amazon :D
    #14
  15. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    This bike has points? I have seen them cause about every symptom known to the ignition system.
    #15
  16. DaveBall

    DaveBall Long timer

    Joined:
    Sep 30, 2009
    Oddometer:
    1,163
    Location:
    Vancouver Island
    I bet the whole problem is the bolts holding the rear fender on. It just has to be because I heard of a firend of a friend who knew a guy whose wife's cousin's son's friend had that exact same problem. He pulled the whole bike apart down to a big pile of little pieces. When he put it back together and finally got those little bolts back holding the rear fender on, and tried to start the bike, it ran perfectly. So obviously it must be those bolts.

    Seriously, check out those little springs on the advance weight. If they are not working correctly they will cause the weights to not work correctly and you will find that at idle and work OK at slight acceleration, but as soon as you start to try and ride it and put some throttle into it, it will start missing and doing all kinds of weird stuff. Basically if the springs are not working correctly your advance will not work correctly. Simple and cheap fix. Give it a try.
    #16
  17. camgregus

    camgregus riding gently now

    Joined:
    Feb 24, 2006
    Oddometer:
    3,014
    Location:
    on the banks of the mighty mississippi, AR side
    and snort. I am missing one of those bolts!

    I'll check the springs.

    Oh yeah, not point ignition. Stock hall sensor, renewed and lubed in 09.
    #17
  18. DaveBall

    DaveBall Long timer

    Joined:
    Sep 30, 2009
    Oddometer:
    1,163
    Location:
    Vancouver Island
    Missing one of those rear fender bolts? There's your whole problem right there. Now make sure you get the right bolt. Has to be made by the elves in the Bavarian forest, and come with the BMW logo stamped into it. No other will do!!! If you use anything else, the front wheel will start to wobble really badly and may even fall off. :lol3
    #18
  19. Stagehand

    Stagehand Imperfectionist

    Joined:
    Oct 6, 2004
    Oddometer:
    27,363
    Location:
    Shawangunks
    :lol3
    #19