BMW 450 enduro (merged) threadfest...

Discussion in 'Thumpers' started by Max Kool, Mar 4, 2007.

  1. ErwinE

    ErwinE Adventurer

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    This is what I have experienced as well. Slow riding, on a straight trail or tarmac, after more demaning work. Feels like the throttle is closed and immediately reopened, twice per second. Happens more when the engine is hot. Possibly related is that my G450X backfires when changing to a lower gear or generally reducing speed.
  2. CRUX

    CRUX Unicorn Tamer

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    Well described, we seem to be having the same issue. I do not pop on decel however.
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  3. BiG DoM

    BiG DoM African Adventurer

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    I would say TPS or lamda sensor.
    Backfiring on deceleration is often an indicator of a leaky exhaust seal between end can and header.
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  4. CRUX

    CRUX Unicorn Tamer

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    Is there any realistic troubleshooting/repair to be done to the TPS and O2 sensor besides replacement?
  5. Drumbrakes

    Drumbrakes Been here awhile Supporter

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    Has this only started happening recently? This sounds like the behaviour that many owners get on the CCM GP450 (uses the BMW 450 engine with a husqy ECU and their own map).
    Some blame it on the second throttle plate. It could be it sticks or moves too slowly.
    Some owners remove it completely and say that helps, but if I felt mine wasn't working I'd rather fix it, than bin it.

    I'm more inclined to point at the ECU switching from a TPS (throttle position Sensor) based fuel map to a MAP (Manifold Air Pressure) map, causing the dip, and switching back again, causing the surge.
    This happens if the fuelling on each map are different at the points where they switch across at low revs and low throttle.

    A TPS sensor reset might help. I don't know how to do that on a BMW ECU though...

    magwych and CRUX like this.
  6. ErwinE

    ErwinE Adventurer

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    Thanks, will have a look. I noticed that I can prevent most of the backfiring by keeping the throttle firmly closed when changing gears. I might have developed some lazy habits on bikes that are not prone to backfiring.
  7. CRUX

    CRUX Unicorn Tamer

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    Hey Drumbrakes,

    In a way yes. It has been without issue for the last few months, but it has always done this sporadically since original purchase. Just popped up again. I have heard about that second butterfly valve, but also feel like the BMW engineers understood what they were doing. Maybe not...
    There has got to be a solution
  8. CRUX

    CRUX Unicorn Tamer

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    If only we could just plug into tune-ECU and rectify such an issue.
  9. Drumbrakes

    Drumbrakes Been here awhile Supporter

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  10. djroszina

    djroszina Long timer Supporter

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    Is your bike running reduced power map or is the high performance plug installed?
  11. CRUX

    CRUX Unicorn Tamer

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    Reduced power map always
  12. djroszina

    djroszina Long timer Supporter

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    Like others said, I would look at Throttle Position Sensor.
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  13. CRUX

    CRUX Unicorn Tamer

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    That TPS reset guide on cafe husky looks like a great place to start, thanks for digging that up. Having a dealer re flash to map 3 seems like a logical step as well. Thank you
  14. CRUX

    CRUX Unicorn Tamer

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    I run the Acerbis X factors and they fit well for me, cables worked out fine as far as I can remember.
  15. Denny Mann

    Denny Mann Long timer

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    Try pulling off your throttle body and cleaning it. When I replaced mine I noticed the old one was so dirty the butterflies did not seat. Rap the exhaust so the fuel doesn't get so hot. This will effect your fuel pump. My bike would shut down and I found if I added fuel it would start up.
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  16. CRUX

    CRUX Unicorn Tamer

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    Thanks, I’ll add this to the list.
  17. Denny Mann

    Denny Mann Long timer

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    I just remembered another issue with the fuel injection system I had. One of the spade connectors on the fuel pump brake off. This caused it to cut in and out from time to time plus there is a ground wire on the cylinder that was loose causing the same issue.

    I had my 450x for 5 years and 16500 mile. Most of my headaches were with the fuel injection and by the time I sold my bike all of that was replaced.
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  18. CRUX

    CRUX Unicorn Tamer

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    I see, I’ve heard about the ground wire issue. Out of curiosity, how did you manage to put 16,000 on the clock? Lots of woods riding or did run run some TAT or BDR’s?
  19. HighTechCoonass

    HighTechCoonass Living the Dream....

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    Anyone have accessories for their G450x laying around? Looking for a safari tank and a rear tail rack.

    [​IMG]
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  20. djroszina

    djroszina Long timer Supporter

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    I saw your bike is for sale, new plans for it emerge, or farkling it for better sales responce?