What is Twin Spark

Discussion in 'GS Boxers' started by irishcurtis, Feb 12, 2009.

  1. irishcurtis

    irishcurtis Adventurer

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    AFAIK, Twin Spark on BMW twins began in the 2004 model year. Bottom line, what is Twin Spark? In the airhead days (and Harley twins, too), dual ignition meant 2 spark plugs per cylinder. Local dealership tells me that BMW Twin Spark means the plug fires on both the compression and exhaust stroke. This suggests to me an emissions benefit rather than a performance benefit.

    What's the real deal?:ear
    #1
  2. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    Your local dealer, and you, are correct.

    Jim :brow
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  3. PRW

    PRW living @ 11.5740741uHz Supporter

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    There's likely an emissions benefit, but my recollection is that it cured the old "surging" problem that many owners experienced. Personally, my 2003 has never surged, but it seemed to be an annoyance for others. I don't recall if the second spark also contributed a few more ponies of performance, but it may have.
    #3
  4. Deans BMW

    Deans BMW Granpa Hoon

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    Two points.

    Typically BMW Boxer twins fire their spark plugs on every stroke only because it is an easier set up, does nothing for either power or emissions.

    Starting in the '04 model year the Beemer Boxers have had two spark plugs in each cylinder, helps emissions, power and mileage. San Jose BMW has been dual plugging Boxer Beemers since the '70's for power and mileage, also to eliminate surging in the early oilheads.
    #4
  5. paladinwest

    paladinwest Been Around

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    In the R1200 engine it is two plugs firing in the same cylinder to increase engine efficiency. The lead/lag between the two plugs can be varied by the motor electronics depending on load, rpm, etc. The R100 engine used what has been called a "wasted spark" ignition where the plug(s) in both cylinders are fired together. In this case one cylinder is at the end of the compression stroke (the cylinder that makes power) and the other is at the end of the exhaust stroke (the wasted spark). This is done to simplify the ignition system and does nothing to increase power or decrease emissions.
    #5
  6. flars

    flars Been here awhile

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    Short answer: Yes.
    Long answer:
    BMW twin spark has two plugs per cylinder.
    BMW has always fired both cylinders at the same time without regard to the number of plugs (which agrees with what the dealer told you).
    Therefore, since the intake timing is 360 degrees out, you get a spark to start the power stroke on one cylinder, and the spark plugs on the other cylinder fire at the same time, which is the start of the intake stroke on that cylinder. Or something like that.
    The dealer was half-, sorta- right, but didn't give the whole story.
    #6
  7. spafxer

    spafxer Long timer

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    A lot of these terms are used interchangably:

    To me : Dual (Twin) spark is two spark plugs in the head to fire at the same time for better combustion, emmisions, and in the case of the boxer engine, drivability.. Helps prevent surging when cruising.

    Wasted spark is just that the ignition does fire on every revolution. The exhaust stroke spark does not help reduce emmisions to my knowledge. It's easier to design this system. Harleys have this. I don't know if boxers use a wasted spark design or not.

    Dual Igntion is 2 completely seperate redundant ignition systems. Used in aircraft for safety reasons..


    Spafxer -
    Puts dinner on the table & motorcycles in the garage :D, Airframe and Powerplant Mechanic by trade. And no I did not stay in a Holiday Inn Express last night...:clap
    #7
  8. Anorak

    Anorak Woolf Barnato Supporter

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    Twin Spark began in 2003 on the 1150 Rockster.
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  9. Global Rider

    Global Rider Alps Adventurer

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    Actually January 2003 give or take a month depending on the model. In the US they called them 2004 model years...even though they're really 2003s. :wink:


    Twin Spark (aka Dual Plugged) and Wasted Spark are two different things. They don't necessarliy have to co-exist.

    Honda inline fours and many others with two coils, but two leads (1-4 and 2-3) coming out of each employs the wasted spark system to keep components down. I don't think they considered emissions.

    The OEM single plugged BMW airheads employed the wasted spark system...one coil on my GS.
    #9
  10. PRW

    PRW living @ 11.5740741uHz Supporter

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    Yup. I was a victim of this model year stupidity by BMW. Bought my '03 in December '02, only to find out that a month later, they added dual-spark. Needless to say, I was very pissed... :ruskie
    #10
  11. longwaytim

    longwaytim Been here awhile

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    My 03 GSA is a twin spark... canadian model
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  12. dyrlege

    dyrlege Norwegian adventurer

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    The same was used (maybe still is) on other two-cylinder engines witout two plugs per cylinder, like my Honda CMX 250 1985. I prefer my 04 R1200 GS for everyday riding, though! It has such a lot more!
    #12
  13. rcpmac

    rcpmac n00b

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    My 1985 R80 AirHead is a twin spark model
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  14. lkchris

    lkchris Albuquerque

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    No it's not.

    It didn't come from the factory dual plugged. It's a conversion using aftermarket parts. And, the conversion accomplished nothing.
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  15. GS Addict

    GS Addict Pepperfool Supporter

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    Tell that to the many who did this mod. They will set you straight.
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  16. Bill-66

    Bill-66 I don't even know... Supporter

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    Dood..you pulled up a thread..from when hippee's roamed the earth..WTF?

    Go to the basement..tell them bastards you are there to bring beer and bacon sammichs back up to G Spot..to try an make amends..

    :fpalm


    :lol3
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  17. Chat Lunatique

    Chat Lunatique aka El Gato Loco

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    BMW Press release...2004

    http://www.r1200gs.info/pressrelease.html

    Quote:
    Featured in all BMW Boxers since 2003 (with the exception of the 850cc power units), dual ignition has been further modified and improved on the R1200GS. The auxiliary spark plug is now arranged at the outer edge of the cylinder, the ignition timing of both plugs being freely programmable as a function of load and engine speed in order to further optimise running smoothness, emission management, and fuel economy. Referred to as "phase shift", this adjustment process is maintained consistently all the way from part load to full load.
    In practice, this means different ignition timing points on both spark plugs in defined control map areas. When approaching full load, where dual ignition no longer provides any benefits, the phase shift effect is so large that the spark crosses over on the auxiliary plug in the expansion cycle (60 degrees at TDC). For all practical purposes this corresponds to single ignition on the central spark plug under full load.
    #17
  18. Bill-66

    Bill-66 I don't even know... Supporter

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    I think that was answered..four years ago....when the thread started..:deal:lol3
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  19. JetSpeed

    JetSpeed Naviator

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    I had something opposite happen to me.
    I traded in a dual-spark 05 GS for a new GSW and was ecstatic to learn that they had done away with the dual spark-spark system......I wonder why the change back?
    #19
  20. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    I would imagine they felt it was unneeded with a better ignition and fueling system. The second spark system added weight and complexity.

    Jim :brow
    #20