990 engine vibration.

Discussion in 'Dakar champion (950/990)' started by Parx400, Jun 8, 2016.

  1. speedy 1

    speedy 1 Wizard

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    When sitting on the stand and running in neutral is the engine vibration constant from idle to red line ?
    #61
  2. Parx400

    Parx400 Long timer

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    Yes. It use to have a little vibs at 5k when on the gas hard. Now it's just vibes from idle to redline. All the other lc8s I have riden you can't feel any vibs on the bars, racks, foot pegs etc. mine is super buzzy.
    #62
  3. Parx400

    Parx400 Long timer

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    Back pressure and out side temp are the only things that make it better or worse. I keep thinking it's fuel related since the bike no longer smells of gas when idling. Use to smell a little rich. I have changed filters, the pump the disconnect and the whole TB set trying to see if that would fix it. No change at all. When it cold out the buzz is not as bad. When it hot it's real bad. Hands butt and feet go numb.

    With fmf q4s baffles in the bike does not vibrate as bad. Pull them out it's worse.
    #63
  4. Parx400

    Parx400 Long timer

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    I would like to put a dual wideband in it to see what's going on AFR wise. The cost of a dual sensor that's going to record stuff is so much I would rather get a PC and wide band.
    #64
  5. speedy 1

    speedy 1 Wizard

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    Increasing the back pressure results in reducing the vibrations points to a leaky exhaust valve. IMHO
    When checking valve clearances in the past has there ever been a valve with very tight specs ?

    Maybe a low cost mixture check ...
    When racing karts as a teen I used to use exhaust temp to adjust mixture.
    My memory is 900F at WFO on the longest straight.
    A thermistor wire / thermocouple hooked to a volt meter can read temp.
    #65
  6. keener

    keener Speed changes you.

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    Couple of things...
    It's runs better when cold out and worse when it's cold...there that's a classic sign of lean mixgure at least on one cylindar.

    Infrared tempreture gun is a simple and easy way to check idle mixture as Speedy suhgested. If you see a significant difference that would confirm fueling issue. The hottest cylindar is leaner. Point the laser to the header the same distance away from the engine for both heads.

    I wouldn't get a PC just yet. You bike ran fine with the map before. Editing the map could only mask the issue.

    Taking the injectors out and testing/comparing their flow pattern is not that difficult. You can send them to a local shop for cleaning (there are shops that only clean injectors) or you can do it yourself with an ultrasonic cleaner. Look up on YouTube for guides.
    #66
  7. Parx400

    Parx400 Long timer

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    The valves are inspect. They have never moved.


    I agree on the one cylinder lean theory. I swapped to a whole different set of TBs and there was no change. That's why I have not pulled the injectors to be cleaned.
    #67
  8. Tangai

    Tangai Been here awhile

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    Did you ever try a different ECU? I ask, because it sounds like it's running lean. I used the ECUTUNE and leaned mine 3% across the board for better MPG, but it then vibrated so much I had to change it back.
    #68
  9. Parx400

    Parx400 Long timer

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    Different ecu is next
    #69
  10. Tangai

    Tangai Been here awhile

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    I was thinking, (dangerous). You might be better off to get a TuneEcu cable and load a new map. I just loaded a 2012 map in my 09, and it runs better and smoother than ever.
    #70
  11. Parx400

    Parx400 Long timer

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    I have the Cablé. I have loaded 5 different maps. No change in vibration. The hoologan map is what I have been running.
    #71
  12. Tangai

    Tangai Been here awhile

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    Well, that's interesting. I did too, but finally installed the stock mapping for stock exhaust (stock everything) for the 2012 990 Adventure. I waited until the next morning and did the 15 minute idle thing. Took it a ride, the more I rode, the better it ran.
    If all else fails, your steering bearings might be loose.
    #72
  13. boat.man

    boat.man Baller on a budget

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    That sucks man, I chased the same issue for almost a year. Rear cyl running very rich and vibration that I could not live with:baldy After trying everything, coils, plugs, injectors, map sensors, 3 different maps, vacuum leaks, valves, valve train, clutch... on and on and on. I gave up and traded it in for a 1290 SA
    Good luck, I hope you can get it figured out!
    #73
  14. Parx400

    Parx400 Long timer

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    So I got an infred head gun. It's super hard to get a reading but measuring at the first welds in the head pipes, about equal distance the rear is about 100 degrees hotter than the front.


    If you test it at the 02 sensors it's close to 400 degrees hotter at the rear. the rear is over 700 degrees at the o2 sensor while idling.

    If you test it at the tips of the fmf Q4s the rear is 50 degrees hotter. You can feel the air coming out of the left side is much warmer.
    #74
  15. RoundOz

    RoundOz Plenty of seasoning

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    It's hard to make IR readings on a level playing field. My experiments with a $30000 IR camera were inconclusive. But it does seem like you are onto something.
    I think my vaibes are related to the clutch. With my clear CJ clutch cover I can see the entire basket and pressure plate shaking about 3-4 mm at idle.
    #75
  16. boat.man

    boat.man Baller on a budget

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    Thats the same thing that mine was doing. My money is on the ECM. Something is causing the rear cylinder fuel injector to be "on" more than it should be. Looking at Tune ECU, the Injector pulse looks normal but thats clearly not the case.
    #76
  17. Parx400

    Parx400 Long timer

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    Interesting. I didnt think that one cylinder could be trying to take off.

    So here is some additional info. A while back when I had the rot 2-1 system I had the bike dyno tuned. There were major issues. Bike had a right off idle rich spot that was impossible to get right. He got it close but It made the bike too hard to ride. There was this dead spot right off idle. I ened up going back to the hoologan map because it was rich down low everywhere and kind of covered up that spot. Bike didn't vibrate back then.

    It was not tuned with a wide band.
    #77
  18. Rharr

    Rharr Been here awhile

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    Try pulling and cleaning the injectors, sounds like you have unequal fueling, either because of a clogged injector or bad ecu/wire sending signal
    #78
    keener likes this.
  19. Parx400

    Parx400 Long timer

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    On my list. I tried a whole different set of TB's off eBay but I have no idea what condition those injectors were.
    #79
  20. Parx400

    Parx400 Long timer

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    So I tired a different ECU off my friends bike. No change. No idea what map is on it.


    Might be time to get a wideband and see what's going on AFR wise.
    #80