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fork height

Discussion in 'The Garage' started by jefft, Feb 8, 2013.

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  1. jefft

    jefft XS650 Junkie

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    What is the distance the forks can be reasonably/safely raised or lowered in the triple trees? I want to lower the front some and don't know how far I can go.
    jefft
     
  2. At about 1" up thru the clamps the brake line union under the triple tree will hit the front fender under full fork compression.
     
    gggGary likes this.
  3. jefft

    jefft XS650 Junkie

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    That won't be a problem because I don't have that union anymore. So same question.
    jefft
     
    gggGary likes this.
  4. jd750ace

    jd750ace Front Toward Enemy

    Reasonably/safely? 1 inch is about all you get for modern high performance sportbikes, and an XS is not modern, high performance, or a sportbike, but it does have more relaxed steering geometry. If you want more drop than around an inch, I'd do it internally with a lowering kit.
     
    gggGary likes this.
  5. 5twins

    5twins XS650 Guru Top Contributor

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    Actually, about all you can get is near 3/4". After that, the fork lowers will hit the lower tree upon full compression. Pull your springs and fully compress the forks. That will show you the distance available. Like I said, it isn't much. I run mine about 3/8" dropped, not for looks but to improve the ride and handling. Lowering the front slightly is an old racer's trick. It more firmly plants the front end and gives more positive steering input.
     
  6. Dday7

    Dday7 XS650 Member

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    Howdy "5Twins". I'm a total newbie to motorcycles, wrenching and riding. I wanted to rectify all that and thus purchased a 1981 XS650 Special II and took it to the frame. I've painted and am slowly cleaning everything as I reassemble. First and foremost, thank you for all your input on this site, it's been an incredible resource and your contributions are awesome. So thanks. Now to my question specific to this post: Do you run the top of the fork tube or the top of the cap bolt 3/8" inches above the triple tree crown? I pulled my forks apart, put in new progressive springs from MikesXS and have reassembled with new oil but am not sure where they should sit in the tree clamps?
     
  7. arcticXS

    arcticXS XS650 Junkie

    As always, hindsight is 20/20....When you had the forks disassembled, internal lowering would have been easy to do, using something like this kit::
    https://www.hughshandbuilt.com/product/xs650-sr500-fork-lowering-kit-35mm/
    The stock fork has 150 mm stroke, while most modern street bikes have around 120 mm, so I would most likely used a 25 or 30 mm lowering spacer myself. Obviously, with a shorter stroke, correct spring rate and preload, as well as damping becomes more important. An added benefit of internal lowering is that it will make the fork more rigid in bending and torsion.
     
  8. joebgd

    joebgd XS650 Addict

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    On my 80 special the tubes are flush with the clamp. I'll take a look and take a picture of the them and fork section. Does your bike have an adjustable preload. On my 80 under a rubber plug type cap is a mechanism that can be turned with a big screwdriver and adjust the pressure on the springs.
     
    Last edited: May 12, 2019
  9. 5twins

    5twins XS650 Guru Top Contributor

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    I just checked mine and snapped a pic. My tube is 1/4" up, the lip on the cap nut about 3/8" .....

    [​IMG]
     
    figure8 likes this.
  10. XSLeo

    XSLeo XS650 Guru Top Contributor

    Wouldn't longer rear shocks have a similar effect as lowering the front?
    Stock are about 12 3/4 inches long. Going to 13.5 or 14 inch shock, that would add 3/4 to 1 1/2 inches. Maybe a 14 1/2 inch.
    I've thought about doing this. It would increase ground clearance and lean angle.
    Make it easier to get up on the center stand too.
    Leo
     
    Last edited: May 14, 2019
    gggGary likes this.
  11. Dday7

    Dday7 XS650 Member

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    Awesome! Thanks for the helpful pic and prompt response.
    I pulled my springs and one side had the tight coil up and on the other side it was down. Both up now, glad I checked.
    Interesting point on the rear shocks. I ordered the 13 3/16" ones from Mike's at $87 for my rebuild. I didn't get a chance to ride the bike enough to formulate an informed opinion on how it felt before I took it to the frame so, I don't have anything to go off of for comparison. But by reading the various threads, I decided suspension would be an area to update and someone liked the longer ones and was about my size (5' 11" 185 without gear on), so I went for it. Thanks again.
     
  12. Dday7

    Dday7 XS650 Member

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    And yes sir. The shocks on my 1981 xs650 special II have the big flat head screw under the cap as well. I didn't know what it was for until l read your post. Before reading how to service the forks, I tried to loosen them...but they were quite stuck and I felt like I was going to strip them...I though maybe you had to loosen them to get the nut off or something. In any case, not the case...I just had to clamp my upper tube in my vice to keep it from spinning and break the rusted connection. I cleaned them pretty thoroughly with brake cleaner while servicing the forks so I'm guessing they'd turn more easily first. Perhaps I should have used a micrometer to measure how much of that little push rod was extended but I'm hoping they're set to the same depth and all is well. We'll see. Thanks for your input.
     
  13. highboy_coupe

    highboy_coupe XS650 Addict

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    Using an SR500 top clamp lets you drop the front over an inch without having to drop the tubes, which looks nicer.
    [edited because I don't want to give out bad info!]
    60506129_886355541727717_8897884966893912064_n.jpg 60446148_2076262835836779_8849604947461799936_n.jpg
     

    Attached Files:

    Last edited: May 15, 2019
  14. jay760

    jay760 XS650 Junkie

    Depends what bars your using fork tube hit the bars before it will bottom out, mine are taken through by about an inch,
    I use xs500 forks on one of mine they are shorter to begin with
     
  15. arcticXS

    arcticXS XS650 Junkie

    Highboy, first of all, good looking project! But I cannot see how using a flat top triple is different from having the tubes protrude past the stock XS triple. The conflict at full bump is between bottom triple and fork sliders, and possibly between front wheel/fender and exhausts/frame.

    Dday,
    Clamping tubes in the vice is not really good practice, it is better to loosen the fork plugs while it is clamped in the triples.
     
    RC4MAN likes this.
  16. 5twins

    5twins XS650 Guru Top Contributor

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    I think you need to give that some more thought. If the SR500 top tree does sit about 1" higher, you are going to have to slide the tubes up through the lower tree another inch to reach it. That is still going to reduce the amount of tube below the lower triple tree available for travel, same as raising the tubes above the original top tree. The 650 fork has about 6" of travel (150mm). In your assembled pic, I'm not seeing 6" of fork tube below your bottom tree. It looks more like 3" or 4".
     
    RC4MAN and gggGary like this.
  17. highboy_coupe

    highboy_coupe XS650 Addict

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    Hi Arctic, sorry, youre right -- was just a neater alternative to poking them up through the clamp.
     
    gggGary likes this.
  18. highboy_coupe

    highboy_coupe XS650 Addict

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    Yeah, my mistake - also my for brace raises the dust covers up, but I have no issues yet with anyhting hitting!
     
    gggGary likes this.
  19. Dday7

    Dday7 XS650 Member

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    Good point! Thanks for the advice
     
    gggGary likes this.
  20. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Loosen UPPER triple clamp bolts, leave LOWER triple clamp bolts tight to loosen the caps, Tight top clamp bolts squeeze the tube against the cap making it VERY hard to remove.
     
    GLJ likes this.

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