Harmonizer Suggestions

Discussion in 'GS Boxers' started by FlatDarkGS, Mar 2, 2012.

  1. marchyman

    marchyman DR and GS

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    With the bike at idle pulling the cable at the throttle body about 1/2 mm should not change the RPM. If the RPM changes within that 1/2 mm the cable is to tight. If the cable pulls more that 1 mm without changing the RPM then the cable is too loose. Repeat on both sides. That is your starting point which gives you about 1/2 mm of adjustment to make the RPM close (I believe the spec is within 15 mbar) at 1400-1800 RPM without messing up the idle.
    #21
  2. Chat Lunatique

    Chat Lunatique aka El Gato Loco

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    Ok, this is where I disagree/get confused. Please correct me here if I'm wrong...

    The "steppers" are actually the idle stops, a mechanical stop, ie.they set up the idle RPM by keeping the butterfly valves in the TB's open a crack to idle. They move up and down to make fast idle RPM as req'd by a cold engine temp. Yes?

    If so then when balancing the TB's at 3500RPM, the idle stops are not touching the butterfly valves any more and do not need to be "parked". I balance my 2010 GS without using my GS911 to park the steppers and have a beautiful , smooth balance.

    No chance of fouling up here if you do not park 'em!
    #22
  3. Chat Lunatique

    Chat Lunatique aka El Gato Loco

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    I balance mine at 3500rpm because that is the RPM of hiway cruising. The tiring handlebar buzz on long trips disappears if you balance at this speed.
    #23
  4. roger 04 rt

    roger 04 rt Long timer

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    I don't have an opinion on what rpm to balance at off idle but there are several ways injectors can be imbalanced leading to the same problems as air imbalance.

    —Different flow rates due to manufacturing tolerance or age

    —Different turn on delay

    —Different turn off delay

    Every several years injectors should be cleaned and checked for matching. My goal is less than 2% difference.

    Then to minimize the effect of injector imbalance you can richen the mixture through O2 sensor shifting.
    #24
  5. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I used to recommend 3500, but have since lowered it to 2500. I agree that 3500 is cruising speed, but at 2500 you get a more accurate balance, and I find that it is still accurate (enough) at 3500 that you won't notice any differences if there are any,

    As for parking the stepper motors, I have done it parked, connected and disconnected and found no difference.

    Jim :brow
    #25
  6. johnjen

    johnjen I've Been Resigned

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    Uh, no, the steppers are an electronic 'stepped' motor that opens (and closes) the idle air bypass circuit. In effect it replaces the Big Brass Air Screw found on the 1100 and 1150 throttle bodies. They electronically (from the fuel injection computer) control the idle for each cylinder instead of it being a fixed amount like the older 1100 and 1150 systems.

    Many have reported that 'parking' the steppers is not necessary in order to balance the throttle cables. And while that may be so (I don't have a 1200 to play with this to verify it one way or another) BMW did go to the trouble of providing this function for that reason.

    JJ
    #26
  7. TUCKERS

    TUCKERS the famous james

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    Who on this Earth can measure .5 mm at a throttle cable and with what?
    #27
  8. jaymboze

    jaymboze Adventurer

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    Totally agree with JVB's comments on this one.
    I have done the sync several times now with the use of my Gs911 to park the steppers and without, and cannot see any difference at all.
    Always balance at around 3000-3500 rpm which seems to work well.
    Only have to make minor adjustments each time to balance the throttle bodies back into sync with each other.

    When at idle they are not matched but does not effect any noticeable difference in performance.
    As JVB says, it's best to do the sync after a valve adjustment.:clap
    #28
  9. jaymboze

    jaymboze Adventurer

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    PS:
    I have also started to run an injector cleaner in the fuel every now and then to help clean out any junk in the injectors and fuel lines.
    #29
  10. marchyman

    marchyman DR and GS

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    Eyeball it. I bet you can guestimate 1 mm. .5mm is half of that. :deal

    The point is that there should be some small amount of movement that doesn't cause an RPM change. If you get an RPM change right away you don't have any slack.
    #30
  11. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I do it like this:

    Works reliably.

    Jim :brow:
    #31
  12. Chat Lunatique

    Chat Lunatique aka El Gato Loco

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    Thanks John! I had the operating principle mixed up. Thought the stepper moved the throttle plate.
    #32