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Thread: G650GS Sertao Tach problems.

  1. #1

    G650GS Sertao Tach problems.

    Here's hoping someone might have a remedy for this problem.. I can't be the only one.
    So there I am, riding along at around 3-4000rpm when the tach suddenly jumps to the redline, the red tach light comes on and it starts to bounce of the rev limiter. The engine is still at the same rpm, but shuts off like it had red lined. I pull in the clutch, wait about 5-10 seconds and the tach goes back to normal. I let out the clutch and off I go again. This repeats 30 seconds later. If I keep the bike below 3000 rpm it won't hit the limiter when the tach jumps, but riding around at 40mph gets old fast.
    I've had the re-flash which fixed it for two weeks. I've changed the fuel pump, which fixed it for a couple of weeks as well. It sometimes stalls at idle or when I accelerate away from a stop.
    I'm open to suggestions, thanks.

  2. #2
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Welcome to the forum!
    How old is the battery?
    Can you hookup a way to monitor charging voltage while you are running?
    Gary
    "You can do good or you can do well. Sooner or later they make you choose." MI5
    Mod Squad
    2009 F800GS 1994 TW200

  3. #3
    Thanks, O.M.
    I know from my MDX that a weak battery can cause unusual issues. I had put it on my charger and it had indicated a full charge. Perhaps even though it says that it's still not putting out the the required current. I think I'll try a fresh battery just in case. Thanks for the tip, I'll post the results.

  4. #4
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    Had the same problem. Chased issue with 2013 650 GS swapping out various parts, CPU, fuel pump, fuel filter, throttle body, stick coils. Always come back to the fuel pump. Not saying it was it but the problem finally went away when I swapped out the stock fuel pump that comes in a carrier (very expensive) for an inexpensive aftermarket pump from e-bay.

    If the battery fix does not resolve your issue I have one of those inexpensive fuel pumps sitting around, PM me.

    Wayne Koppa
    Grayling, MI
    #71,449

  5. #5
    design to inspire fun 777AIA's Avatar
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    Quote Originally Posted by jdominicp View Post
    riding along at around 3-4000rpm when the tach suddenly jumps to the redline.
    When you start up the bike, do you stay off the throttle, and let it start and idle on its own? These thumpers get funny issues when you don't.

  6. #6
    The start-up procedure for this bike : Turn the key to on position, wait 10 seconds, press starter and hold the button down for 1-2 seconds after it's fired up. Don't touch the throttle.
    Seems a bit much, doesn't it. I'm used to bikes with carbs, turn the key, hit the button, off you go!! It's a 2014, you think they'd know how to build a reliable F.I. system. Apparently not.

    I had one of the first F.I. bikes, a '81 Kwack GPz1100. Nice bike , terrible F.I., I ended up ripping it all out and installing a bank of carbs, massive improvement. Hmm...There's an idea...

    When I have time I'm going to try swapping the battery for new, and go from there.

    Thanks for your input.

  7. #7
    New battery, still the same problem.

  8. #8
    Registered User
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    Quote Originally Posted by wkoppa View Post

    If the battery fix does not resolve your issue I have one of those inexpensive fuel pumps sitting around, PM me.

    Wayne Koppa
    Grayling, MI
    #71,449
    Just saying

  9. #9
    Registered User Guenther's Avatar
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    I don't know specifics about the F650GS. The symptom sounds like a faulty sensor on the cam shaft or its wire connections.

    /Guenther
    2017 F700GS

  10. #10
    Registered User drneo66's Avatar
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    Do you have a volt meter on the bike? I'd be curios to know what the battery voltage is at when the bike is at idle, below 3000, and above 3000.
    Current: 2007 BMW R1200RT, 2013 F800GS
    Former: 1995 BMW K75S, 2009 BMW G650GS
    MOA Member #:150400, IBA#: 37558

  11. #11
    Look at the symptoms:

    The tach symptom is caused by its receipt of spurious signals. It may be caused by a defect in the wiring for the Hall Effect Sensor or ignition trigger. If insulation breaks down or the wire gets pinched it is possible to get arcing within the wiring bundle causing the false signals to the tach.

    Obviously if the HES wiring has a defect you may get inconsistent ignition when starting the bike or when it is running.

    So the first thing to do is to thoroughly inspect and verify as good the wiring for the HES and associated ignition parts.

    The other possibility would be arcing within the coil which could send spurious signals to the tach and also obviously mess up starting and running.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  12. #12
    Registered User Guenther's Avatar
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    The ignition sensor is in the alternator housing on the right side of the motor (#3 in the picture, part number 12117652904).

    G650GS Ignition Sensor.jpg

    It is either the sensing unit (lose or defect) or, something else lose inside the alternator housing. Could also be the wire/connector of the sensing unit going to the engine control unit (ECU).

    The tachometer just reports what the ECU is 'seeing'.

    /Guenther
    2017 F700GS

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