990 engine vibration.

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

  1. Parx400

    Parx400 Long timer Supporter

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    I have changed mufflers but not the header pipes. Vibrated with both.

    I'm going to try another left side tank off and friends bike to see if it's the filter/ pump.
    #41
  2. MortimerSickle

    MortimerSickle Semi-Adventurer

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    Though maybe fun, I would leave on at least the header pipes.

    I have heard that to have cold air right next to the valves is bad for them- maybe so, maybe not, but why risk it?
    #42
  3. Parx400

    Parx400 Long timer Supporter

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    I put an update to the first post.
    #43
  4. chrisBTSC

    chrisBTSC Been here awhile

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    It's July... in Sacramento... There is no such thing as cold air. :lol2
    #44
    Crazy Carl and DistortedAxis like this.
  5. knobbyjoe

    knobbyjoe Adventure and dirt rider

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    #45
  6. Parx400

    Parx400 Long timer Supporter

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    I don't think this is an exhausts issue. it started when I had the 2-1 on it and still does it with 2-2.

    I'm swapping fuel filter then trying another set of TB's. I snagged a set off ebay for 128 shipped. harness and all.

    If neither fixes it I guess it goes to the stealership.
    #46
  7. Crazy Carl

    Crazy Carl Drank the Kool-Aid

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    Would this friend be me? If so you're gonna need a key to my house as I'm gone this Saturday through the following Sunday. Totally fine, just let me know.
    #47
    knobbyjoe likes this.
  8. Parx400

    Parx400 Long timer Supporter

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    Been a year and I still ave not solved this issue.
    #48
  9. Pariahtize

    Pariahtize Miscategorized

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    Have you brought it to the KTM mechanics yet?
    #49
  10. wyomingpat

    wyomingpat Adventurer

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    I reset my chain tension too tight and got the same problem. Seems it likes 2" of slack.
    #50
  11. Parx400

    Parx400 Long timer Supporter

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    Mine vibrates in neutral not moving. My guess now is it's fuel related. Bike does not smell rich like it use to.
    #51
  12. speedy 1

    speedy 1 Wizard

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    A bit of stretch ... here are a couple of things to check ...
    It is possible to have great compression and still have a leaky valve. With the symptoms of an odd exhaust sound it probably on that side rather then intake. Symptoms of a leaky intake is it pops back out the intake.
    Balance weight sheered the key and has slipped to the wrong spot.
    #52
  13. Parx400

    Parx400 Long timer Supporter

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    How do you test for a leaky valve. Bike has good compression. No popping for anything like that.
    #53
  14. Rharr

    Rharr Been here awhile

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    you have ridden other 990's and noticed there is a distinct difference between your and the other one?
    #54
  15. Parx400

    Parx400 Long timer Supporter

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    Yup. 4 others. One of those is set up identical to mine.

    Mine use to not do this. It was fine for years.

    I'm going to swap ecu with somebody next.
    #55
  16. speedy 1

    speedy 1 Wizard

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    Tool works thru the spark plug hole with the piston locked at TDC. No doubt plenty of YouTube Videos to watch.
    Official tool has gauges and measures leak down pressures against time. TOOL EXAMPLE
    My DIY version ...
    Weld a short piece of tube to the steel part of a disassembled spark plug on one end and an air connector to the other end.
    Remove headers and intake for visual access.
    Rotate piston to TDC with a wrench thru the little plug on the generator side.
    Use same wrench to lock the crank from moving. Tie to foot peg or ...
    Pressurize the cylinder with air. 100 psi is enough to show results.
    Spray the base of the valve with liquid and look for bubbles.

    Besides changing the ECU try some different ignition coils.
    #56
  17. Parx400

    Parx400 Long timer Supporter

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    Ok. I will give it a try over winter. It does not seem down on power at all. It runs like the the TB 's are way off but they are not. I even swapped a whole other set of TB's on it. No change.

    The only thing I can say has changed is the no longer has a rich smell to it at idle. I have swapped lots of maps and nothing changes.
    #57
  18. keener

    keener Speed changes you.

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    Have you tried a different map?

    The reason I'm asking is that in the last few months that I've been working on my map with Wideband as sensors, I've seen vibration at various rpm ranges. These were when AFR of one cylindar was too different from.the other. Correcting the map meant much less vibration in that rpm range. I also see higher vibration when engine is running too lean at certain rpm, around 15 AFR or higher.

    So my theory is that it could be one of your injectors not functioning %100 because it's partially clogged. Making that cylindar too lean.
    #58
  19. Parx400

    Parx400 Long timer Supporter

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    I have used lots of different maps. Even used another set of TB's. No change.
    #59
  20. Parx400

    Parx400 Long timer Supporter

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    I do agree it could be fuel related. I have even thought about getting a power commander and auto tune to force the bike to run the same afr. That's not s cheap option though and the bike use to run nice and smooth with the hoologan map.
    #60