KTM 990 front end wiggle

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by smj, Mar 3, 2013.

  1. smj

    smj Been here awhile

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    Never had a bike do this before. Ever. Between 30 and 50 mph, let go of the bars, the grips start to dance without me - front end shimmy that does not go away but gets worse the longer I leave the bars unattended. Granted, this is usually not something you'd do for long amounts of time, but it is very worrysome to me, no bike has ever done this before. This one only has a couple hundred miles on it. Hands on the grips damps it out, for now, but I am not a trusting soul when it comes to things like this. Back to the dealer for sure, but any ideas on what might be going on? Thanks! steve
    #1
  2. BigNastybrp

    BigNastybrp Big Nasty

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    stock tire? bad tire, out of balance, lose triple?
    #2
  3. Orangecicle

    Orangecicle On a "Quest"

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    Is the front tire new? What type of front tire is it? Is the front a Scorpion? I find that Scorpions on my bike do this almost every time. You will definitely notice it as the tire ages and starts to cup.

    If you check your sag and find that it's about right, I really would not worry about a little wiggle on decel like that. Experiment with other front tires. I'm about to try a Heidenau K60 for the first time.

    So, the solution is pretty simple. Set sag appropriately, find a front tire that you like . . . and don't ride around letting go of the bars. :D
    #3
  4. DirtyADV

    DirtyADV Long timer

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    Scoprion shake:

    <iframe width="560" height="315" src="http://www.youtube.com/embed/uzzqR_iJrUg" frameborder="0" allowfullscreen></iframe>


    Will get worse as the tire wears all mine have had it, next front on the stock rims I will try something else.

    /Johan
    #4
  5. Deviant666

    Deviant666 Been here awhile

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    Scorpion front 101...if you ride mostly on road try the Continental Trail Attacks...they transform the bike...I ride with them off road too...hard pack, they do fine...loose staff, look for something else....
    #5
  6. TerraThumper

    TerraThumper Meesta Fwank

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    My OEM Scorps had a shake at about the same speed range. Not so much side to side shake, rather just felt like severe imbalance, yet the tire was re-checked for balance. I found the tire carcass was “out-of-round”. Easy to see when spinning it in the garage using a grease pencil. A new set of tires resolved the problem.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    #6
  7. smj

    smj Been here awhile

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    Thanks for the input! My bike is new, the tires are stock. I now have a couple 100 miles on them, and the problem is not getting any better. This past weekend I let go of the bars while coming down a canyon, on a straight length, to ease a muscle or two... I could watch the shake go from zero, to hard enough to really worry me. Put the hands back on the bars, which took a bit of focus to actually catch them, and the shake damped right out. Still, I'll go back to the dealer and see what he might have to say as well. Sounds like the tire might be the problem, although I'll have the dealer at least check the triple and balance, and I'll also check the sag - though I think that is set right. I'll also look at the out-of-round possibility. Thanks again everyone! First time I've seen this.
    #7
  8. BIG-E

    BIG-E AKA; Mongo-E

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    +2!!

    I can't for the life of me figure out why you would let go of the bars?? I usaually have a death grip on mine. And the blisters to prove it.:deal

    As said, it is the tire, try a 606 or TKC for more road work.
    #8
  9. larryboy

    larryboy Chopper Rider

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    Probably too much pre-load on the back or the front springs are too soft for you. Tires don't cause this, a certain tire might make it feel worse, but you need to make sure you have the suspension setup right before we start blaming tires.
    #9
  10. woodchuckexc

    woodchuckexc Been here awhile

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    Don't worry. Every one of these bikes does that with a stock tire.
    #10
  11. chrish4ku

    chrish4ku Been here awhile

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    Ya - it depends on the tire. I have thought my front end is phuked then changed tires - all good..

    Hmmmm
    #11
  12. FakeName

    FakeName Wile E Coyote SuperGenius

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    My stock tires were great. My Dunlops are not.

    On the freeway, I recite the mantra:

    Weebles wobble, but they don't fall down..
    #12
  13. laramie LC4

    laramie LC4 crash test dummy!

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    first, all you should ever need is a light grip on the bars, any more and your wasting energy.

    i have 5 bikes in my garage and the ONLY one i can't let go of the bars on is my 990. the other bikes are all dirt bikes, without balanced tires, and i literally can stand up, let go of the bars, and coast down a hill doing a "christ the redeemer" pose and track as straight as an arrow. my 990 scares the shit out of me within 1/2 a sec of releasing my grip.

    i took my 990 in because of this head shake issue and got the same "look" from the mech when i said, "let go of the bars." that worries me because there is absolutely no reason that a bike should not track straight unless something is out of balance. in fact, the centrifugal force acting upon the tires wants them to roll straight. it takes something bad to change that. i have seen video of a guy riding a 1800 goldwing hands free, he hits the bar with his hand to try and cause it to lose control. it wiggles for a sec, then straightens back out. all without any hands on the bars.

    i have eliminated all other possible causes on my bike besides the tire. it is balanced, i have changed the suspension settings, i have tightened the steering head, checked the rear pre-load on the shock, everything. the only thing left is the tire.

    currently i have a new tire being warrantied by KTM for my bike. should be here by tuesday...

    just my $.02,

    laramie :beer
    #13
  14. laramie LC4

    laramie LC4 crash test dummy!

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    :rofl:rofl:rofl:rofl:rofl
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  15. smj

    smj Been here awhile

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    OK - I took the bike back to the dealer today, it only has a couple 100 miles on it. He said that they have seen this before, on a couple of bikes. That Scorpion has had some tire problems and they change out the tire - end of problem. The dealer also said they thought the original problem was now fixed, but now and then one still shows up, maybe an older lot number. However, they will also check the rim, balance, we looked at sag, make sure everything is tight, and a couple other things. The mechanic looked the front tire over, and said it looked cupped already. It is supposed to snow 12 inches or so starting tomorrow night through Saturday, so I don't think I'll need the bike this weekend, should get it back early next week. Oh, yeah, no cost to me.

    By the way, letting go of the bars... Wisdom or folly, probably up to each rider to determine that one! But I found a problem on a new bike, now it's getting fixed... For free. By the way, ~45 mph was the "sweet" spot, where the wiggle really built up strong - and no I did not have the brass to see just how bad it might get. My experience over the years is that if a bike has an instability, you fix it, at the least find out the souce... Might not sound like it, but I do try to avoid the pavement!

    Thanks everyone, I'll let you know the end result.
    #15
  16. chrish4ku

    chrish4ku Been here awhile

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    Good to know they will true and fix this. I may bring mine in too. It looks to wobble, and I don't need the same outcome as big nasty.
    #16
  17. Katoom990

    Katoom990 Adventurer

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    I have a 2011 and started to experience the wobble after the bike had 4,000 miles on the odo.

    It seemed to get worse when I had luggage loaded in the back. Another 990 rider said that it was just the fact that the front end was "light". Not sure I buy that.
    #17
  18. Sporting Wood

    Sporting Wood I

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    9 times out of 10 its the need for more rear preload on the big KTM. Also could be bent wheel, bad bearings, forks too low in the trees, bad tire, etc...
    #18
  19. jfink

    jfink Can't get there from here

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    I have a 2011 990 Dakar which has wobbled from day one in the same speed range as yours, 35 to 45 mph. Took it to the dealer who said it was the back tire. I replaced the rear tire, twice. It now has 25,000 miles and wobbles like a duck. I have had the front tire "trued" and balanced, no joy.

    I agree, you don't let go of the handlebars, but at this point I can still feel the wobble even when gripping the bars and when standing and not gripping tightly it will still wobble.

    Right now I am riding with my buddy around South America. He also has 2011 990 Dakar with a wobble since day one in the same speed range. He also has changed his tires three times and that has not helped his wobble either. This is not a tire problem. There is just something just not right about these bikes. But, I do have other friends who have 2011 990 Dakars and theirs does NOT wobble.

    I may try changing the level of the forks in the triple trees, new progressive springs in the forks, new stem bearings and the front wheel fix from Slavens Racing.

    It bothers me that a bike with this heritage has this kind of issue.
    #19
  20. smj

    smj Been here awhile

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    jfink - thanks for that post on the front wheel fix from Slavens Racing. I'll make sure to check the rim strip on mine, and probably go with the rim tape as well. Best of luck to you on your trip, hope you enjoy South America. If you make it to Santa Cruz, Bolivia - watch out for the cobble stones in old town!
    #20