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Thread: Fixing Earthing Problems - Why and How

  1. #11
    Senior Member mmcn49's Avatar
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    Interesting write-up, thank you for taking the time to write and post. Had an issue 9 or 10 years ago that could have been an Earth, (Ground) problem. Like you I ran bonding wires, (but not as extensive). I did not run a tap through the bolt holes but when I polished the aluminum I immediately coated it with a Nickel based Hi-Temp Never Seize.

    Why?

    -Never Seize is "Conductive". It is not a dielectric or non-conductive
    -Nickle based Hi-Temp Never Seize is not messy and does not contain copper
    -Immediately because the cleaned up aluminum surface oxidizes very quickly

  2. #12
    Senior Member outthere's Avatar
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    thanks from a Buell newb

  3. #13
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    Good stuff! Thanks, JV!

  4. #14
    Hey all
    I'm glad people think its useful BUT... it would be much more useful if info on Lightnings and Firebolts ground locations were here too.

    For instance Kona said he thought the Lightning had the battery earthed on one side of the rear subframe and the ECM on the other side. If that's true, it makes what is a relatively unimportant extra earth wire on a Uly (between the 2 earth points inside the same LH subframe), HUGELY important on a Lightning. If that's the case, a Lightnings ECM is held at a voltage above battery negative by any corrosion, not only of both earth joints to the subframes, but also the joint between the cast subframe halves and the frame to subframe joints.

    Is that the same for the short wheel-base City as on the long wheelbase SS? (since they presumably have different subframes??)

    What about the Firebolt's earth points?

    Remember this Grounds/Earthing thing is all about the grounding of the ET and O2 sensors back the the ECM. All the other sensors have earth return loops in the wiring loom from the sensor and back to the ECM again, only the ET and O2 are earthed through the engine and frame. I'm not saying the earthpoint on the steering head is not important to keep clean, but its not in the same league as the ET and O2 grounds back to the ECM and battery as far as the misfire, hiccup etc is concerned.

    Can people who know please add the extra detail? Thx - jv
    Last edited by John Vreede; 08-03-2018 at 07:09 AM.

  5. #15
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    Really good information here JV. If I had known half of that 2 years ago I would have solved my issue then and save a bunch of $. I think the level of info is just right so keep on posting good diagnostic information. Partial posts = partial understanding of the issues. I prefer to spend 5 minutes reading over 1 day of wrenching and guessing (and yeah... That is definitely experience talking).

    It will be a few weeks before I can get time to tear into the bike again but I have the 2006 xb shop manual for my 2006 xb12ss. I'll take a few pictures of the ground locations and post that. If you want particular items (pics or manual) post the list you want.

    Suggestion:. Is it possible to post a checklist for others to walk through? You seem to have the best handle on this. If this could be codified into a list it might make someone else's life a lot easier.....

    Thanks again

  6. #16
    Just confirmation of Kona's recollection that the SS has the ECM earthed to one side of the rear subframe and the battery to the other will be enough.
    If true then people can go look whether their bike is like a Uly or like an SS, and do the appropriate thing.
    If not we'll have to wait for someone else to chime in with the confirmation.
    Am working on the checklist thing as an attachment you can download - is that what you had i mind? - jv

  7. #17
    Senior Member mmcn49's Avatar
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    Hi JV – 07, XB12STT. The metal plate under the battery, to which the ECM is mounted is bolted to the Sub-Frame at two locations. The cable from the Battery's Negative Terminal is bolted to the sub frame at one of the bolts. The ECM housing including the mounting bolt holes is all plastic, no need for any additional bonding.

    On Saturday I:

    -Ran a 5/16” tap through the Tie Bar mounting holes in the main frame and center tie bar mount
    -Immediately coated the chased threads with conductive never-seize
    -Chased the 5/16” mounting bolts with a die and wire wheeled until shiny
    -Coated with never-seize
    -Mounted a tinned 16 AWG copper conductor with ring connectors across the ground strap
    -Ran another 16 AWG wire from the center tie bar mount side directly to the battery's negative terminal

    On Monday I went for a 509 mile run. The engine has never run so smooth. Though not huge, the improvement is more than noticeable and well worth the effort. It also looks like there was a 1 to 2 MPG fuel improvement but that can be subjective.

    Thank you JV. Any other suggestions?

  8. #18
    Hi mmcn
    Thanks for looking but it's still confusing me a little.
    Can you go look at your bike and find where the ECM earth leads are bolted to the frame - they're the ones under the seat, that exit the wiring loom at the same point and both are crimped into one lug.
    Are these wires taken to earth under the same bolt as the battery negative cable? Or on opposite sides of the subframe from the battery negative cable as Kona thinks the SS ones are?
    I'm pleased the bike went better than before, but cleaning the earths can only make it go as well as the factory intend.
    The fact that it did go better means your earths were dirty. Doing what you did obviously removed enough the of the earth problems to allow the ECM to read the sensors properly - for now.
    If you didn't clean/protect the frame and subframe joints there is likely still some high resistance in the starter motor circuit, i.e. your starter motor will not be turning over as freely as it could - thats the value of a hefty cable from tiebar to battery negative. A 16SWG copper wire can only take just over 10 amps so while it helps the ECM, its no help to the starter motor.
    Also the ECM earth-lug to battery negative connection, the connectors where wires from ECM join the wire to the ET and O2 sensors, and the resistance of the wire from ECM plug to its earth lug are all areas that could go wrong in the future and bring back the dreaded misfire.
    The wire from the coil hold down bolt to the battery negative I think works for people when the tie rod connection, you just cleaned&protected, is dirty. Induced voltages are a sort of a black area I know very little about; I have to take for gospel what more knowledgeable people say. If the Air Force believe in them and protect against them, then I have to too, thats why I put in that extrawire.
    I don't think any of these will make your bike go better than it does now, but you'd be protecting against a recurrence in the future - jv

  9. #19
    Senior Member mmcn49's Avatar
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    Hi John,

    >>>Can you go look at your bike and find where the ECM earth leads are bolted to the frame - they're the ones under the seat, that exit the wiring loom at the same point and both are crimped into one lug.

    The two ECM Earth Leads are bolted to the sub-frame on the RIGHT side. The battery negative cable and a black 12-14 AWG conductor are bolted to the sub-frame on the LEFT side. Many years ago I ran a 16 AWG jumper wire between the left and right side so that the ECM Earth leads are connected to the negative battery cable copper conductor.

    >>>If you didn't clean/protect the frame and subframe joints there is likely still some high resistance in the starter motor circuit, i.e. your starter motor will not be turning over as freely as it could - thats the value of a hefty cable from tiebar to battery negative.


    When I ran the bonding wires wasn't thinking of the "Macro" picture, only the sensor grounds. I have a hunk of new 4 AWG cable. In the next few days I redo the work/wiring. Before starting anything else I need to know.

    Thanks,
    Ed
    Last edited by mmcn49; 08-09-2018 at 09:45 PM.

  10. #20
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    XB12Ss grounds

    JV:
    To answer you question on a check list: Yes- you have the idea I was after. Some codified series of steps of what to check and what to look for (ohm maximum for example). A "did you check this" list for those ignorant of what to look for (like I was when I started).

    For your question on where the XB12Ss ground are:
    On my bike i have the battery restrained by the stock strap and a hose clamp (this really helps with shaking the terminals loose). I also have an old sponge jammed under the factory strap to push the seat up and off the connectors.IMG_20180812_154200.jpg

    On the left side is the battery to battery tray ground as well as two grounds from the main wiring harness. IMG_20180812_155221.jpg

    On the right side is the (I believe) computer leads that also go to the shift linkage. IMG_20180812_155453.jpg

    Underside of the fuse box shows the leads better. IMG_20180812_155945.jpg

    I presume that all buells use metal battery trays for connecting the grounds.....IMG_20180812_155048.jpg

    Finally, I ohm tested my ecm ground and the ground path to the battery terminal. Max resistance was 0.2 ohm (and I only got that high once).

    If you need more information, let me know.



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