F800GS unstable at higher speeds

Discussion in 'Parallel Universe' started by Baiazid, Dec 17, 2012.

  1. Baiazid

    Baiazid Been here awhile

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    Hi,

    recently I had 30.000km service and I asked them to replace tires as well.
    Service consisted also in changing fork oil.
    I have now Haidenau K60.

    I went for a trip next day after the service and noticed on highway when I go beyond 110kmph, bike starts to be very unstable. Front fork starts to shake semi-violent (left and right). If I slow to 105 .. all is fine.

    Before this I used to go 160kmph with no drama.

    What can be? :norton
    #1
  2. Reaver

    Reaver Outta Here

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    Did they balance the tires? If the aignment was off it would track funny but since it's speed related I'd say an out of balance front wheel. Bent rim?
    #2
  3. Baiazid

    Baiazid Been here awhile

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    Saturday I am going again into the service.

    Rim has a small bend (had that for last 2 years) and never affected my stability at any speed.

    Tires look balanced (they have extra weight added on one side) but I cannot tell if was done properly.
    #3
  4. sorebutt

    sorebutt Long timer

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    If it is a tire balance issue it should be an up down type vibration. I'm gguessing front wheel alignment. Loosen the pinch bolts that hold the axle on one side. Then bounce the front end up and down a number of times. Then tighten the pinch bolts and take it for a spin.
    #4
  5. Gangplank

    Gangplank Advenchaintourer

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    Could be a bad tire. Ive had a few sets of TKC 80's that got the death wobble over 80 mph.

    Did they mount it right?
    #5
  6. catweasel67

    catweasel67 RD04

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    sounds lke a wheel balance issue to me - maybe a weight fell off?
    #6
  7. Angryrican

    Angryrican know nothing all

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    It's most likely the tire, there are a few threads about K60's doing this when brand new and it goes away after a few hundred miles of break in
    #7
  8. Loutre

    Loutre Cosmopolitan Adv

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    <-- What he sais. It'll go away after a couple hundred miles. Gives you another reason to get the bike out there and ride it... It's for safety reasons of course :wink:
    #8
  9. JRWooden

    JRWooden Long timer

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    A:
    Do you know how that works?
    What's going on in the first few hundred miles?
    #9
  10. ragtoplvr

    ragtoplvr Long timer

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    check your tire pressure. Now. Unstable on a motorcycle is most commonly a low or over inflated tire. You can pick up a nail in the dealer parking lot. If pressure is right, then you can look for other stuff. If you are recommended to run 42 psi for tire life, try the recommended pressures in your manual.. The longer life might not be worth it.

    Rod
    #10
  11. Dr E

    Dr E Chasing after theory

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    Have you checked your preload on your rear suspension? When that gets off, one of the signs will be front end wobble or instability.

    Good luck!
    #11
  12. runnin4melife

    runnin4melife Been here awhile

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    I don't take my TKCs above 80mph because it feels as if the bike is floating, put a set of road tires and I can go well over 120 with no problem. Same rims, same suspension just the tires. Some are worse than others, My first set of TKC80s, the front was really bad but I didn't have my new suspension then so I just rode it out and they went away (I pulled and checked balance, and whether the rim was bent or true, all was fine). I have never ran the K60s so don't know about them. I was looking at them for my Alaska trip so I hope they don't have an issue at 80+...
    #12
  13. DoWorkSon

    DoWorkSon Been here awhile

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    Just got k60's on my F8... They are fine at 80mph+... No issues, feel similar to stock street tires..... They have less than 50 miles on them too. Just a slight vibration at low speeds(15 mph), but not bad
    #13
  14. Angryrican

    Angryrican know nothing all

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    I don't, I'm going by the scientific evaluations of the members of this forum:rofl

    joking aside it's mention quite a few times in this forum in different tire threads, I personally have never had the issue but I'm am super anal about tire pressure setting on and off road and dialing in suspension
    #14
  15. JRWooden

    JRWooden Long timer

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    Feedback: It worked for me, thanks Gary! :clap
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  16. JRWooden

    JRWooden Long timer

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    Yeah ... good luck with that ........ :lol3 :freaky
    #16
  17. F800ekelley

    F800ekelley Adventurer

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    Have the same bike and tires i can not go above 75 tires are balanced and are perfect i had pirelli scorpions on before and crusied at 80mph all day
    #17
  18. Baiazid

    Baiazid Been here awhile

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    Yep, I had pirelli scorpion until last week. Could do 160Kmph with no problems....
    #18
  19. F800ekelley

    F800ekelley Adventurer

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    Its def the tire heard other guys on diff bike have same thing its a 50 50 tire so i guess i cant complain about no high speeds
    #19
  20. Angryrican

    Angryrican know nothing all

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    To your point another thing to consider is rider position and whether you are using handlebar risers since they also will position the rider a bit back and up(you have to factor the steering angle) shifting your body back unweighting the front even more. Curious to see if guys under 175cm tall using bar risers have this issue since they would not be tall enough to keep their body forward with risers. I tried 20mm risers for a bit and hated how the bike handled with them, I also had a Rallye Moto damper on that raised the bars 20mm and it put the bar in a very un-natural position for my personal use and it was bad enough to out weigh the benefits of the damper
    #20