2006 Bmw r1200gs flatspot/stuttering at full throttle

Discussion in 'GS Boxers' started by Skapegoat, Jun 27, 2020.

  1. Skapegoat

    Skapegoat Been here awhile

    Joined:
    Sep 10, 2012
    Oddometer:
    156
    Location:
    Ireland
    I've done a few searches using similar words but haven't really found anything exactly like my issue.


    The bike starts perfectly.
    It idles perfectly.
    It does not cut out at slow speed or coming to a stop.

    The issue appears when moving, specifically at full throttle in 5th and 6th gear as it seems the bike struggles to get through a 5,000rpm flat spot.
    At full throttle in 5th and 6th (where it is most noticeable but happens in all gears) the bike suffers power loss and backfires as if fuel starved.

    If you keep full throttle on it will eventually work it's way through it but it's not pleasant.

    If I roll back off the throttle to say 50% then it runs through it no problem.

    This hesitation also happens at 3000rpm (not at full throttle) but it seems to rev trough this quicker yet it is still not pleasant and in the wet the unpredictable nature of this fault does not inspire confidence.

    The issue can be intermittent but is mostly always there.

    From what I have been reading up on the famous oul internet some people have just replaced spark plugs and this has resolved the issue so that is my next step.
    I had not replaced them yet as they were recently changed on the service history.


    I am also concerned it may be coils or fuel pump.
    The fuel pump was replaced under warranty a few years ago.
    The coils seem original.


    Has anyone had this issue?


    I have had the bike since Febuary service so is as follows.
    New oil,
    Oil filter,
    Abs flush,
    Valve clearance,
    Gearbox oil,
    Final drive oil,
    Air filter.
    Tips sensor reset.
    Some other small bits.

    I have lubed all electric connections.
    Replaced headers with decat headers.
    New end can.


    None of the above has in anyway resolved this issue.

    It appears it's worse after warming up hence why I'm leaning towards coils or plugs at present.
    Yesterday the first 10mins of a spin the bike was perfect then the issue raised its head.
    I stopped after 30mins.
    Restarted my journey and with the warm engine the issue was evident straight away.
    I can kind of ride around it but life's to short I want it sorted.

    Love the bike but this is a pain in the ass of an issue.
    Thanks to all you wiser men than me in advance.

    Skapegoat Ireland.
    #1
  2. GS Addict

    GS Addict Pepperfool Supporter

    Joined:
    Sep 24, 2006
    Oddometer:
    7,380
    Location:
    Sunshine Coast B.C.
    #2
    lewisjr1 likes this.
  3. Skapegoat

    Skapegoat Been here awhile

    Joined:
    Sep 10, 2012
    Oddometer:
    156
    Location:
    Ireland

    That's my feeling too.
    I don't know anyone with coils but will ask about local bike groups or breakers before I take the plunge on 400e coils.
    Thanks for the idea.

    Christ they are expensive.:muutt
    #3
  4. GS Addict

    GS Addict Pepperfool Supporter

    Joined:
    Sep 24, 2006
    Oddometer:
    7,380
    Location:
    Sunshine Coast B.C.
    Early coils of that vintage did have issues.
    #4
  5. Callisto224

    Callisto224 Long timer Supporter

    Joined:
    Jan 5, 2010
    Oddometer:
    7,096
    Location:
    GA
    Is there any value in swapping out primary and secondary coils or is this not possible?
    #5
  6. GS Addict

    GS Addict Pepperfool Supporter

    Joined:
    Sep 24, 2006
    Oddometer:
    7,380
    Location:
    Sunshine Coast B.C.
    The secondaries are 90 degree. Won't fit.
    #6
    Callisto224 likes this.
  7. Skapegoat

    Skapegoat Been here awhile

    Joined:
    Sep 10, 2012
    Oddometer:
    156
    Location:
    Ireland
    Update,

    4 Shiney new iridium plugs installed.
    Went for a spin 30km out the bike ran perfectly. :D
    Turned it off (on purpose as sometimes this brings on the issues) and tried really hard to bring on the issue again the flat spots were back but a lot less pronounced. :hmmmmm

    Now I'm wondering did a bad plug just magnify the natural flat spots in the lean part of the rev range.

    SO I suppose what I'm asking is do all 2004 to 2012s have slight hiccups in fueling?
    Certain revs, throttle openings in certain gears.

    I could live with it the way it is now but will get it dyno'd out.

    May try a few more miles to no to see if it gets gradually worse. :baldy
    #7
  8. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

    Joined:
    Feb 11, 2005
    Oddometer:
    91,401
    Location:
    Alexandria, VA
    Depending on your sensitivity to it, the Hexheads had a slight flat spot around 4200 RPM. Bad plugs or stick coils definitely make it worse.
    #8
  9. Steve W.

    Steve W. Boxer Pilot

    Joined:
    May 14, 2005
    Oddometer:
    928
    Location:
    Upstate South Carolina
    #9
  10. Desert Skies

    Desert Skies One brick shy...

    Joined:
    Mar 2, 2004
    Oddometer:
    2,613
    Location:
    Tejas
    I agree with the coil theory too. Been there, done that.
    #10
  11. Skapegoat

    Skapegoat Been here awhile

    Joined:
    Sep 10, 2012
    Oddometer:
    156
    Location:
    Ireland
    For completions sake ill update this issue incase anyone ever has something similar.

    I brought it to a dyno center and explained the issue.
    The mechanic there also expected a coil but said he would double check a few things.

    He said the throttle bodies were perfectly balanced.
    The fuel pump was strong and he said the issue appeared to be on the RHS cylinder as this had a lower heat reading with the laser thermometer.

    He could only get the fault to replicate on the Dyno once at 3,000 rpm and due to the low power revs he felt it was the angled coil at the bottom of the cylinder was at fault.

    So 70euro for some clarity on the demo.
    168euro for the replacement lower Rhs right angle coil.

    The issue persisted.
    So armed with a spare coil it swapped the lhs right angled lower coil for the spare and the issue persisted still.

    My gut feeling all along was the straight stick coil was the issue (didn't know which side) due to the drive being effected on heavy throttle and at 5,000rpm.

    100euro more and the bike runs like a dream, right hand side upper coil was the issue all along.

    Thanks for the advice on here 340euro later I figured it out....:clap
    #11