HELP! Vibration problem

Discussion in 'Dakar champion (950/990)' started by crazybrit, Jun 12, 2011.

  1. FormerInmate 020619

    FormerInmate 020619 Guest

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    My '04 950 Adventure has the exact same vibrations as your bike and has had ever since I bought it last year. The thing is that the vibrations on my bike come and go, though. They are mostly there, but once in a while they disappear. When such a magic moment occurs you better be on a really nice piece of road, 'cause you never know how long that joyous moment will last. It could be half an hour or a couple of hours.

    My observations of the phenomenon are quite similar to yours. The engine pulls good and runs smooth even in low rpms. It's only the vibrations on rpms from 5k and up that's causing frustrations. Apart from what is said earlier in the thread I could add a few things. I've noticed that the exhaust sound changes slightly when the vibrations disappear. The noise level (yeah, I've got Sebring silencers) is normally really annoying. When you happen to have a blessed day (more like hour) without vibrations the sound level is much lower than "normal". The funny thing is that the engine performance at the same time gets even better.

    I have no idea of what is causing the vibrations. The gut feeling I'm having, and have had even before I started reading this thread an hour ago, is that it's not anything mechanical. I have tried a few things:
    1. Dr_Bean fuelpump mod (pump wasn't working ok due to worn out contact)
    2. Removing EPC (SAS already removed)
    3. Running a tank with carburetor cleaner
    4. Checking TPS (within spec's, albeit at the lower limit)
    5. Checking pulse sender (don't remember values, but a bit low in voltage I think)
    6. Replacing battery
    7. Checking coil resistance

    Worth to mention is that when I first removed the coils I noticed some sooty dirt/residue on one of the coils. It smelled a bit like burnt electronics, but I didn't reflect on it for too long. Then I believe someone in this thread suggested that the coils could be suspected. As a matter of fact I asked my KTM mechanic about the coils only earlier today when the bike was at the dealer for 30k km service and we spoke about the problem. His response was that he didn't think they were part of the problem. I'm not so sure about that... The intermittent nature of the vibrations makes me believe it has something to do with ignition or the electrical system somehow.

    When I bought the bike it was equipped with HID lighting. I know such equipment can destroy a lot of electronics in cars, even properly mounted. I think it can cause transients in the 12V system that in the long run break sensitive components. The most sensitive part in our bikes' electrical system is the ECU.

    At last, a question:
    Does anyone know how to properly check the ECU for damages?
    #41
  2. crazybrit

    crazybrit Long timer

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    I bought spare coils and a spare black-box/ECU. No difference. I also checked the TPS and it's correctly calibrated.

    I can reproduce the vibes on the side-stand (same vibration points as when moving). Reproduces with fuel-pump (Dr Bean) disconnected and the carbs gravity fed [post fuel pump] from an aux-tank.

    There is no way to test the ECU other than with a bench tester. The manual mentions one but I don't think there is a KTM part. Maybe Kokusan has one.

    For your bike, if it happens when moving, I'd check the tire balance.
    #42
  3. FormerInmate 020619

    FormerInmate 020619 Guest

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    New chain, new tires, no difference. Depressing the clutch while riding makes the vibrations disappear. In combination with the fact that the engine performance increases and the sound changes when the vibrations are absent, I can not think of anything but the engine as the source.

    Have you double checked the pulse sender/pickup on your engine? The service manual states that the distance between the ring and pickup should be 0.6-1.0 mm.

    On a 2000 km trip last week I used fuel with both 95 octane and 98 octane. I could never be sure, but my impression was that the vibrations and barking sound from the exhaust under load got worse on the 98 octane. It makes me think that there might be something wrong with the ignition timing. The higher octane fuel should ignite later than the fuel with lower octane under the same conditions, so if ignition timing is too late I think that the symptoms ought to be more noticable. At least I know for sure that there is an opposite ratio between the amount of burbling at deceleration and engine performance. When the engine runs at its best and has no vibrations the backfiring and burbling is at a minimum.

    Since there are no ways to check ignition timing on these things, how can we be sure that the ignition is correct? There are no knock sensors, so the control unit only relies on the pulses from the pickup ring, the TPS, the octane selector and the gear sensors. But come on, should the ECU be interested in the gear selection for ignition timing? I thought that it only used it for regulating the EPC. Does anyone know for sure what parameters are used and how many ignition maps the ECU has? How can you know what map it's actually running on?
    #43
  4. crazybrit

    crazybrit Long timer

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    Head2Wind kindly loaned me a set of carbs. I installed them and I don't perceive any change in the vibes.

    MortimerSickle (Ken) came over to my place today. Comparing both bikes at 6000 rpm on the side-stand, the vibes on mine are pretty significant compared to his, I think we both agreed on that.

    There is a huge difference in the vibration transmitted into the handlebars. I have the BRP triple clamp, his is stock but I've checked the damping rubbers on the BRP and they are perfect and everything is torqued to spec.

    My bike isn't insured/titled so Ken didn't want to ride it, so I rode both bikes in my local neighborhood. His is a lot smoother above 5000 but mine is definitely still rideable.

    I'll insured/retitle mine in January and we'll both go on a longer comparison ride to see how they compare on the freeway at 75mph .... but I'm committed to just riding it now while keeping me eyes open for a decent price low hours 2006/later replacement motor. Everything that can be checked has been checked.
    #44
  5. gefr

    gefr Life is a trip

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    That could compare to engine rpm and decide if it is the crankshaft rpms or the camshaft rpms. I think this would be helpfull...
    Just shooting in the dark here.
    Cheers.
    #45
  6. crazybrit

    crazybrit Long timer

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    I'm done troubleshooting it. Will ride it until:
    a) I find a new motor and swap -- any pointers to low miles 2006/later 950/990 motors for-sale appreciated
    b) current motor blows up
    #46
  7. DIRT DERRICK

    DIRT DERRICK Adventurer

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    Kevin Yorks on the UK KTM forum filled his handle bars with silicone sealant and said it cured his vibrations!
    Could be a cheap fix!
    #47
  8. ICERIDER

    ICERIDER Adventure Rider

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    If you have a friend in the aviation industry. Perhaps slap a vibe check on it and see what comes out of it.

    I know it wouldn't explain why it changed from good to bad but is it worth trying another rotor/flywheel?

    Also borrow a stock triple clamp/bars and try, although you do say it comes through the pegs as well.
    #48
  9. crazybrit

    crazybrit Long timer

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    I still have the OEM clamps, previous owner included them. Same for the KTM exhausts but both have been in a box since I've owned the bike.

    As I said earlier, I'm planning on hooking up again with MortimerSickle in the New Year once my bike is titled/insured so we can both ride including some freeway. I'll probably reinstall the OEM triple clamps and OEM exhaust for this - not because I think they are involved in the vibes - but just to be as close to MortimerSickles bike as possible. My FMF Q2's are definitely way throatier than his stock KTM headers. Apples to apples :D

    After this, I'm DONE farting with the bike. Not one second more troubleshooting.
    #49
  10. crazybrit

    crazybrit Long timer

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    Picked up a replacement motor today. A 2004 with 23k miles. Running before removal so I was able to test ride. Much less vibey than mine, we'll see if it feels similarly inclined once it's in my chassis :evil First off, move it 40' from the car to to the garage. Once the vibey 06 motor is out, getting it into the basement (workbench) is going to be fun.

    [​IMG]
    #50
  11. MortimerSickle

    MortimerSickle Semi-Adventurer

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    Come on Tony, buff up. :D

    [​IMG]

    [​IMG]

    129.4 lb.
    #51
  12. crazybrit

    crazybrit Long timer

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    and that's without the hoses :D
    #52
  13. MortimerSickle

    MortimerSickle Semi-Adventurer

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    Please don't tell us about the weight of your hose.
    #53
  14. crazybrit

    crazybrit Long timer

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    Nice. That just earned you one days community service at motor-switch school. PM me for times. You can get credit against future offences if you bring a floor jack.
    #54
  15. MortimerSickle

    MortimerSickle Semi-Adventurer

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    Jack? What do you mean jack? What makes you think I have a jack.

    [​IMG]

    I don't know anything about any jack.
    #55
  16. Black Hills

    Black Hills Long timer

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    is it only under load? Did you adjust the chain by chance? my '11 990 had vibes in the same rpm range if the chain was too tight.
    #56
  17. cycleman2

    cycleman2 Long timer

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    I've read this whole post and I can't recall if all of this started after you did the first work or was it there before. To me it sounds like ignition related as from the plugs you are getting lots of fuel, but it could also be that the carbs aren't pulling together. Also with carbs or fuel injection I've always done the sync in the 3000 rpm range. It almost sounds to me like both carbs aren't pulling together.

    I imagine you've got the motor out by now but if you haven't, try setting some cable slack at both carbs, say 2 mm to make sure the throttle plates are closed. Set all mixture screws at their stock setting and set your idle at its stock rpm. Then put the sync gauge on and leave the front cable alone and at 3000 rpm adjust the back carb to the front so you are getting the same vacuum reading. Blip the throttle a few times to make sure that it works properly and you still have a reasonably stead vacuum reading at 3000 rpm.

    I'm also not sure about the choke set up on a KTM but if it isn't coming off all the way you will get running issues ( too rich ).

    I operate in the KISS principle as a lot of times it really is something simple.
    #57
  18. crazybrit

    crazybrit Long timer

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    PLEASE no more replies about trying to debug this and that with the original bike. Everything has been tried. I realize people are just trying to help but it's not the chain, it's not the carbs (see previous post, whole different set tried), it's not the ignition (different black box and coils tried). This has all been commented on previously and checked.

    Like I said, "reboot time".
    #58
  19. Dan950ser

    Dan950ser Two Wheeled Addict

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    Eldon took great care of that bike and engine. I know first hand so I hope this is a fresh start and an end to your ongoing nightmare. Good luck and I will be checking back for the updates.
    #59
  20. crazybrit

    crazybrit Long timer

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    thanks Dan, it was my first motor 3-way, hopefully it'll all go well :D
    #60