Front end bounce at 40-50 mph on my 2012 990 Adventure

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by neilwm, Oct 3, 2012.

  1. neilwm

    neilwm n00b

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    Nov 1, 2010
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    Hi all,

    I picked up a new 990 Adventure last week. I love the power and how smooth the gear box is. My only problem so far is a front end bounce at speeds between 40-50 mph. I took it back to the dealer today for it's first service and had them rebalance the tire which they did. They added an additional weight to the tire and test rode it. The tech. said that it rides like every other one now. On my way home from the dealer which is a two hour ride from my house it appeared the problem was indeed solved. No more bounce at the stated speed range. As I got into the first village with a 30 mph speed limit the bounce was back. The rebalancing essentially moved the bounce from 40-50 mph to 20-30 mph. Has anyone experienced anything like this?
    Is this like the tech said "The way they ride" ? Is there something other than tire balance that I should look at? The Service Manager wants me to drop the bike off for them to troubleshoot for a few days. I really don't want to be without a bike that long with this being the best time of year to ride. Thanks for any and all input.
    #1
  2. SideRoad

    SideRoad Adventurer

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    Check to see if the tire is out of round. Mine was and was replaced under warranty
    #2
  3. GrenDesb

    GrenDesb Been here awhile

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    Typical of the stock Scorpion front tire.
    #3
  4. hontri

    hontri Global Bummer!

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    My made in Germany front Scorpion worked fine.When it wore out i replaced it with another but this one was made in Brazil. I then had the same problem as you.Replaced it with a Heidenau.Now smoooooth as butter.
    #4
  5. lenny6753

    lenny6753 Adventurer

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    Yes, I've had the same issue. Actually, I still have the same issue at times. I have had three sets of scorpions and a set of heidenau's and they have all done it. It seems to always occur with mine between 30-40 mph. I have had tires balanced, rebalanced, and balanced again with no luck. I have adjusted the suspension, no luck. I noticed mine the most when I rode to Alaska in 2010. It actually became so bad when I was in Montana I was afraid I would have to end my trip.

    I had the tires balanced again and it helped for a while but it still happens. I thought mine was because I had the bike loaded down with panniers and camping gear(about 60-70 lbs) on the back end. I received lots of advice on this forum and was very grateful but the problem still exists. The recommendation that made the most since to me was that my front fork springs were too weak and that the front end was bouncing(po-going) and that I should have heavier springs or a different fork oil to make them stiffer. I don't know if either would help. I weigh about 225 lbs with all my riding gear.

    Good luck, I hope you find a solution because I have not.
    #5
  6. neilwm

    neilwm n00b

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    Thanks for the replies. What is the best way to check the tire? Do I remove it from the rim?
    #6
  7. bikepharmer

    bikepharmer Baja is on the way

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    Jul 31, 2008
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    May seem odd, but my bike is doing something similar and it may be the fuel pump. Is it a wobble, or surging at a speed or rpm?
    #7
  8. neilwm

    neilwm n00b

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    I believe my issue is either a tire or suspension. I have not notice any surging. The fact that changing the balance of the tire, changed the speed that the symptom is introduced seems to prove that.
    #8
  9. caryder

    caryder Been here awhile

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    With the bike up in the air, rotate the front wheel with something close to the tire to see runout front to back and side to side. If nonexistent then force the brake pads away from the brake rotor to allow the wheel to rotate freely, then check the static balance again by trying to find the heavy point. If the tire or wheel is clearly out of round or still out of balance ask the dealer to replace the tire and or true the wheel instead of just trying to balance it again. If this seems to be an unresolvable "feature" of your setup you may want to try a dynamic balancing product.

    I don't buy the weak spring argument. If it were wheel chatter sure, it's a suspension issue, but this seems to point to an out of round or out of balance problem.


    Chuck
    #9
  10. neilwm

    neilwm n00b

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    I'll give that a try Chuck, thanks
    #10
  11. GSAragazzi

    GSAragazzi Long timer

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    Hi, not an expert but if it looks like this change your air pressure until you find the sweet spot.
    [yt]KOl1EDiK2e8&feature=youtube_gdata_player[/yt]

    [yt]v=KOl1EDiK2e8[/yt]

    Tried to moved but couldn't:
    http://m.youtube.com/watch?v=KOl1EDiK2e8
    #11
  12. ride-for-life

    ride-for-life Been here awhile

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    I had the same problem, mine was out of true not only will a wheel get out of true left to right but up and down too just adding weight wont solve the problem, will need to be trued. but said above it could be tire, suspension or wheel.
    #12
  13. what car??

    what car?? down the road

    Joined:
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    There are a few different methods that you could check for wheel roundness, whether side to side or up and down. As a former auto tech I would use a mounted dial indicator, a magnetized one or one that is attached to a pair of vice grips to check specific measurements. Someone thought they needed them more than I though, I have not replaced them since I no longer work in the field. There are ones with a wheel that is cool, as it can ride on the rim itself (great for side to side movement with tire still mounted), remove the tire for up and down movement.

    Since I no longer have the dial indicator, I used the next best thing. I shod the rims with new tires :rofl.... Nah, actually used a pencil.... Well actually did get new tires.... I had some weirdness with the Scorpians, I think most people have. But a few basic things to check, tire pressure, make sure it's set correctly for your conditions and load. Once that is set, test ride your bike (using the same road(s) and preferably in the same part of the lane, gets you a litmus test if you will) adjusting the suspension both rebound and dampening, I also checked the headset, I also checked the tension of all the spokes, I don't have an actual spoke torque wrench for this, but what I did use was an application on my eyephone: I play guitar and used the Guitar Toolkit ap set to 'tuner' and used a long screwdriver and taped the spokes individually in the same location for each spoke and checked the 'tune' of each one. They were all within what I would call 'tuned'...

    If that doesn't do anything and the problem still persists. Get the bike on the center stand and make sure you can affix the handle bars so they have no lateral movement. I then took the front brake calipers off the bike and tied them to the crashbars so as to have less resistance. I took a pencil, actually (4). Yes, I can be kind of anal, but then again as a former auto tech, comebacks kill your reputation and your check. So with that said, what I did is took two pencils and mounted them perpendicular to the rim (one on each fork), I used tape and tried to make them as level as I could, actually tried to use a mini mineral spirits level (did I mention that I could be anal about some things????:rofl At least I can laugh at myself!). I mounted the sharp point (as sharp as you can get them) in the middle of the rim as close as I could without touching the rim itself (actually thought about using a feeler gauge for this, but chose not to, perhaps should have :lol3....) Then I took the other two pencils and mounted them, one on each fork, at angles just clearing the tire at the highest point of the rim itself, this if for up and down measurements. Once all this tedious work was completed I went and had a good homebrew, (my own) whew:freaky, actually a couple.

    Of course I'm sure you can guess what I did then.... Well maybe not, I was hungry, got me a snack..... Once all those formalities were completed, I spun the wheel. I did it as fast as I could and also as slow as I could to check 'run-out' the measurement of wheel movement in this case. I checked many times on each side so I didn't miss anything. For me, everything came out ok, no issues. Another homebrew in celebration :1drink.... Took the pencils off, left the bike on the center stand and went to watch a movie, Diarios de Motocicleta yo pienso....

    Good luck with your issue and hope you get it resolved....
    #13
  14. TheMuffinMan

    TheMuffinMan Forest Ranger Magnet

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    I have this between 30-50 with a tkc up front and a Heidenau on the back. Recently I thought it was suspension and maybe I threw some wheel weights but maybe the tire is just out of round.

    Kind of sucks since I only have a thousand and change on the Heidenau and don't want to toss a $190 tire. I'll probably ride it and deal with it.
    #14
  15. Turkeycreek

    Turkeycreek Gringo Viejo

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    Spend $14 on a bottle of Ride-on. I had a wicked shimmy between 82 and 84mph on new Shinko 705s on my 06 Tiger. The primary reason for the goo was to have the sealant properties but it took care of it. It is a cheap experiment and doesn't leave a mess when you change the tire.

    [​IMG]
    #15
  16. gefr

    gefr Life is a trip

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    Turned out to be worn wheel bearings. Maybe worth checking out.
    Cheers.
    #16
  17. neilwm

    neilwm n00b

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    Thanks for all the replies. Great information, I will post a resolution hopefully soon as I go through all the checks.
    #17
  18. dlrides

    dlrides 1:1.618

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    Springs & suspension settings
    #18
  19. neilwm

    neilwm n00b

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    Took the wheel to a motorcycle shop in my area that can do high speed balancing. First thing he did was to indicate the rim and found it out of round. I spoke to the dealer to tell him my findings and he said I have to bring it back to him or to another KTM dealer to do the warranty work. So tomorrow I will make the two hour trip back with the wheel and see if they can finally resolve this issue. I will keep everyone posted.
    #19
  20. BillyD

    BillyD Been here awhile

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    Sounds like an excuse to upgrade to a Woody's wheel, if you plan to do any rocky off-pavement riding. Doing so might help avoid this:

    [​IMG]
    #20