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Thread: Open Chamber Pain

  1. #41
    Lifetime Team KTMTalk KTMLew's Avatar
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    Default Re: Open Chamber Pain

    Quote Originally Posted by wfopete View Post


    Ok because it was EZ to do and I was curious, I set up a quite un-scientific test for the relationship between compression settings and the amount of travel used. I pulled a 8" thick 12 foot log off my wood pile and blocked it up with some rock and cinder blocks to help keep it in place. The plan was to make successive runs over it with different compression settings to see if going to a harder setting resulted in more travel used. After each series of runs at a particular setting I would turn the compression clickers in 5 turns until eventually I got to full hard compression. I made 3 runs across the log at each setting and measured the amount of travel left over after the three series of runs. All the runs were made in second gear and I tried to keep my throttle/speed consistent to keep the test somewhat legit. Here are the results:



    • 30 (full soft) - 60mm
    • 25 52mm
    • 20 43mm * note this series of runs is a throwaway (Because I did a big stoppie on the way back).
    • 15 48mm
    • 10 44mm
    • 5 25mm
    • 0 34mm (full hard)
    • 0 55mm * note on this run I had purged the air out of the forks that had built up during the pervious runs. I didn't hear much come out.


    Ok you can shoot plenty of holes in this test. The log might have moved or rolled, did I hit the log harder on some runs, was I on or off the throttle when hitting the log and on and on. I get it. BTW; when I was done with the test I had pushed the log about 15 feet from where it was initially placed; cinder blocks and all. But it was interesting to note that there was a downward trend in unused travel until I went to zero clicks out...I didn't see that coming.

    In the end I had made over twenty-five trips over an 8" log in second gear at various compression settings. So what does this mean? Hell if I know. After I made the last run at full hard compression, I turned the clickers back to full soft and made three more runs, the impact transmitted back was less. So despite the forks using LESS travel, when set to full soft/30 clicks out, the impact to the rider was less than at stiffer compression settings using MORE travel. I got a lot more comfortable riding over logs too but I do believe I will take a few Ibuprofen now.

    On second thought you know what I'm thinking about?

    Bottoming cones and drill bits.




    Lower. The. Oil.

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  3. #42
    KTMTalk Member KXcam22's Avatar
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    Default Re: Open Chamber Pain

    Here is pic of my bottoming cones. Cam
    Attached Thumbnails Attached Thumbnails IMG_20160222_194947.jpg  

  4. #43
    KTMTalk Member wfopete's Avatar
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    Default Re: Open Chamber Pain

    Quote Originally Posted by KTMLew View Post
    Lower. The. Oil.
    I plan to repeat the test with lower oil level Wednesday. Although a 8" diameter log is not a giant obstacle and likely would not send the forks into full bottoming of the travel, I find it noteworthy that I still left a minimum of around an inch of unused travel regardless of the compression the setting.
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  5. #44
    KTMTalk Member wfopete's Avatar
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    Default Re: Open Chamber Pain

    Quote Originally Posted by KXcam22 View Post
    Here is pic of my bottoming cones. Cam
    Thanks, much clearer to understand with the picture.
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  6. #45
    KTMTalk Member wfopete's Avatar
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    Default Re: Open Chamber Pain

    I duplicated the same log test I did earlier but with a few twists. First I got a fresh log, this time I went with a larger 10" log. I also added about 400 pounds of rock and gravel to keep it in place.

    Click image for larger version. 

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    Next I brought the oil level in the forks down to 160mm and went out to see if there was any difference in the forks. I did the same test again, that is I started at 30 clicks out and worked my way down to 0 clicks out at 5 click intervals. The result was I used more travel than went the oil level was at 130mm (of course now I was hitting a slightly bigger log that wasn't going to move) but I still have not bottomed the forks especially considering the settings. For the record 1" = 25.4mm



    The results:

    Clicks Out (160mm) (130mm)


    30 29mm 60mm


    25 18mm 52mm


    20 12mm 43mm


    15 23mm 48mm


    10 34mm 44mm


    5 19mm 25mm


    0 19mm 34mm


    I also made one series of runs with one compression adj. full out and the other full in and ended up with 23mm of travel left over. So at the 160mm oil height I did use more travel but I was also hitting a slightly larger log too. Again the higher compression setting resulted in the most travel used.

    I think it's time to punch a couple of holes in the bottoming cones. Again my goal here is
    to get a smooth controllable ride in the rocks and second to use all the travel in the same conditions with the forks set in the middle of the compression adjustment (15 clicks out). If I could get my forks to just bottom or very close to bottoming when hitting the log above at 15 clicks out I think that would leave me a fair amount of adjustment for other conditions.

    Last edited by wfopete; 10-22-2020 at 08:09 PM.
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  7. #46
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    Default Re: Open Chamber Pain

    Quote Originally Posted by KTMLew View Post
    i don't do the last step where he dumps the fluid. Just lower you level by 20mm and see how it works.
    genius ..so simple
    Hangtown,Norcal right side of the left coast

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