990 engine vibration.

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

  1. Parx400

    Parx400 Long timer

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    My 08 has slowly picked up a bad engine vibration. It's to the point where my hands are going numb. It can feel it at idle or on the gas. If you pull in the clutch on the freeway it goes away. Pretty sure it's not the tires and it much worse on the gas hard.

    What should I start looking for?

    Update:

    here is a list of the things I have checked.

    New Plugs
    TB's balanced
    Valves in spec
    Engine mounts checked.
    Compression is good.


    Things to check:
    Fuel filters ( they are pretty new but who knows)
    TB's ( found a used set for 129 off ebay)


    Using a socket extension I felt around the motor. There is no real vibration in the engine. Its all coming through the exhaust system from harmonics or rough running. When the engine and outside air is hot the bike is close to unrideable. Its not too bad when its really cold outside.
    #1
  2. Hoologan

    Hoologan Been here awhile Supporter

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    "It can feel it at idle or on the gas. If you pull in the clutch on the freeway (and let it drop to idle?) it goes away."

    I assumed "at idle" meant when the bike is stationary. No?

    So do you only feel this while moving?
    #2
  3. JoeMongo

    JoeMongo ¿Por dónde?

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    Balance TBs lately? I usually only do so immediately after a valve adjustment or major intake change. Even if you haven't done anything to affect airflow it might be worth the five minutes to check (assuming you have the Snapout installed).

    Maybe one of your secondary flies fell off. Maybe one of you primary flies fell off. :eek7

    Maybe one of your fuel injectors is partially plugged up.

    Maybe the callouses on your hands have gone away due to too many manicures. :ksteve
    j.
    #3
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  4. NeptuneTriton

    NeptuneTriton Been here awhile

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    I had the same problem on my bike not so long ago. I looked at balancing the Throttle Bodies, but they were fine. I then thought maybe I had a loose engine mount, but they were all good. I thought maybe it was the new knobby tires, but like you, once I pulled the clutch in the vibration went away so I knew it was engine related.

    Turns out, my fuel filters were clogged causing excessive vibration in the engine. I replaced them and ran some Seafoam through the first tank and it all went away. Now I know what that symptom feels like and replace my filters at the first sign of it.
    #4
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  5. Parx400

    Parx400 Long timer

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    The bike seems to have gave more Vibs than I remember at idle. Under load its really buzzy, to the point my hands, ass and feet and going numb.
    #5
  6. Parx400

    Parx400 Long timer

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    i'm going to check the balance this weekend.
    #6
  7. Parx400

    Parx400 Long timer

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    Balance seemed to fix most of it.
    #7
  8. Parx400

    Parx400 Long timer

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    Ok The balance did not fix it. It seemed smoother the first time I rode it but now is back to the same. 60 miles to work and my hands feed and butt are getting numb.
    #8
  9. crashmaster

    crashmaster ow, my balls!

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    Possibly drive train related? Very loose chain? Nut backed off the C/S Sprocket?
    #9
  10. Parx400

    Parx400 Long timer

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    The issue is for sure engine related. Last night I pulled the clutch cover off and found 1 pressure plate bolt backed out and 1 only finger tight. That did not have any change on the vibration. I can however say that the out side air temp has a huge effect on it. When I left Sacramento it was not cold out at all and it vibrated pretty bad. When I got to napa it was really cold and the vibs were not nearly as bad. When I leave in the afternoon to go home is pretty hot out and the vibs are horrible. I read on some of the smt/ duke forums people had a similar issue with weird map/ intake / exhaust combos. I did recently go back to 2-2 with a set of akros. I'm going to pull the baffles and see what effect it has.
    #10
  11. Parx400

    Parx400 Long timer

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    Well i tried chain and sprockets just to check that off the box and the vibration is still there. I might be crazy but it feel like its all in the exhaust system. my hand on the engine revving feels super smooth. But there is likes of vibration in the pipes. the tail rack feels like a cellphone on vibrate.
    #11
  12. advrockrider

    advrockrider Been here awhile

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    I had a baffle come loose on my xr650r and it caused some weird vibrations. Took a while to track down but as soon as I removed/fixed it the vibes were gone! Good luck...
    #12
  13. Parx400

    Parx400 Long timer

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    I pulled the baffles to check and it made no difference.

    The vibrations get much worse when the engine is hot and its hot outside. When its cold out side its not that bad.


    A few of my valves are right on the edge of spec. I'm going to adjust them and see what it does.
    #13
  14. keener

    keener Speed changes you.

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    Just to be sure the syncing of carbs is not rue issue, use an infrared temp gun and check the heads' temperature at idle. They should be very close.

    Its easy to sync the carbs incorrectly. Tinny bit of leak makes a big difference.
    #14
  15. motoman250f

    motoman250f Been here awhile

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    seems like on these bikes that if one cyl is working harder than the other you get vibration under load. same point as being unbalanced each cyl is getting the same air but one is pulling harder. is the bike weaker than usual? the fact that it is better when cold could mean one cyl is running rich. id try to run with open airbox just to troubleshoot pull baffles maybe even one at a time,, etc. this is all assuming you trust your sync
    #15
  16. Parx400

    Parx400 Long timer

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    Bike seems to run the same power wise. When it's really cold, like layer up cold it's not really that bad. When it's 99 out in traffic it's unbearable.

    I got a better tool to sync the TB's. Going to adjust valves then sync and test.

    The vibration has slowly gotten worse over time.
    #16
  17. motoman250f

    motoman250f Been here awhile

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    Airfilter can do all this. that would also explain why its been gradual.. you will be creating the same A/F effect by opening up the airbox as running in cold weather. If that makes any difference you might be on the right path. If you pull the cover off you will be bypassing the filter and the bike will run quite a bit different. normally this will create bogs in the rpm because your getting more air than normal but that's the same thing as running in colder weather. Don't run without an air filter for long or in dusty conditions.
    #17
  18. Parx400

    Parx400 Long timer

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    I have an open ITG filter. i have run the bike with the filter off and its still viby as hell.

    Also going to do a compression check while i'm in here.
    #18
  19. RoundOz

    RoundOz Plenty of seasoning

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    As far as TB balance goes, be aware that if you are checking it through the sensors via TuneEcu or other software, it has been reported that they can have an offset compared to each other - a quick check is to swap them or swap the hoses and see if they still show to be in balance.
    #19
  20. motoman250f

    motoman250f Been here awhile

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    I don't know how your going to verify equal pull from each cyl after a trustworthy sync. A/F from each exhaust at a dyno shop?? maybe a ktm shop can help.
    #20