640 Adv stiffer rear spring/forks

Discussion in 'Thumpers' started by Buckster, May 18, 2005.

  1. Buckster

    Buckster Banned

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    Have the "80" rated rear spring on the Adv now, back wheel feels much more "planted" now, still have to tweak up for sag but at standard pre-load it is feeling better for my 200lbs 6'4" frame.

    Some of the front end vagueness at speed has gone away to, money permitting, it will be time to sort the forks next. Should I just up the springs or do I drop them over to WP UK for a re-valve?

    Any suggestions?
    #1
  2. transalper

    transalper Been here awhile

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    Where did you get your rear spring? KTM says it has the 75 for $190 US, but I can't find another source.
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  3. Stobie

    Stobie Mr. Motivated

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    Factory Connection and Mx-Tech are both WP dealers. You shouldn't have to pay more than $130 for a WP rear spring. FC prolly has them on the shelf.
    #3
  4. meat popsicle

    meat popsicle Ignostic

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    Thanks for the link Stobie!

    The WP fork springs are $110.01 (a penny - :doh) - not bad at'all. but putting em in appears to be a biatch! Bet the revalving tain't easy neither... :arg

    The WP shock spring is $119.95 - again very nice prices. :nod
    #4
  5. meat popsicle

    meat popsicle Ignostic

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    Thanks again Stobie! The mx-tech link has a local shop in Livermore, CA

    http://www.imotoracing.com/index.htm
    anyone have any experiece with these fellas? :ear

    Fork Servicing: $90/pair plus parts
    Shock Servicing: $90 plus parts

    MX-Tech treatment (revalve/respring?) $245 per end... :evil

    Nice suspension setup diatribe here:
    http://www.mx-tech.com/tuning_offroad.asp
    :D
    #5
  6. Buckster

    Buckster Banned

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    I got it from the WP agent here in the U.K., it cost about $120 U.S.
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  7. Stobie

    Stobie Mr. Motivated

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    My forks are in pieces on top of my workbench right now. Revalving isn't a big deal if you know what changes to make to the shim stack. Disassembly was really pretty easy.

    Proper fork springs have been harder to come by than the shock spring. I tried Brad Lowe's Racing, but ended up with the wrong springs for both ends, mostly because the LC4's (especially the Adv) are the Rodney Dangerfields of the KTM world. I bought Cugino Pegaso's 80/260 rear spring, and just ordered some fork springs from Mx-Tech.

    The problem with sourcing fork springs is that, even though our bikes use the same basic 4860 WP fork as the '03 and '04 EXC/MXC's, it's set up internally for a 43mm x 485mm spring, instead of the 43mm x 510 mm spring of the RFS bikes, and it's not just a swap of preload spacers. The 510's won't fit without way too much preload being put on them. The one's Mx-Tech has on the shelf are 495mm, and there is plenty of room for that. I just hope the wire diameter isn't too large.

    So Meaty, go ahead, dive in, do your own respring/revalve. The only special tool needed is an inch-pound torque wrench, and I'm thinkin' I 'member you got that covered. :nod

    If you really want to be a tightwad, and have access to a torch and bench grinder, you can stiffen your own springs without spending a dime. But you can only go to about .48 kg/mm. I wanted .50's, and you can't cut the stockers enough to get there without reaching coil bind (coil bind bad). The rear spring would be a PITA because of the powder coating, and the need to machine a spacer.

    Oh yeah, you'd prolly have to spend $10 on shims. :deal
    #7
  8. transalper

    transalper Been here awhile

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    Thanks for the link. You're my hero!
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  9. meat popsicle

    meat popsicle Ignostic

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    thanks for the vote of confidence; the disassembly instructions seemed daunting... :uhoh

    what about all those fancy tools they specify - custom stuff for the WP forks only? Vise-Grips? :lol3

    torque wrench? funny you should ask... this JUST showed up with the mailman:

    [​IMG]
    :evil
    #9
  10. 2whlrcr

    2whlrcr gooligan

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    I put a pair of .46 springs in, I ordered from Enduro Engineering and didn't notice the difference. They seem to be working ok, so I'm not going to take them out.
    #10
  11. Bush Basher

    Bush Basher Adventurer

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    I have cut my springs (forks) and all went well.
    I'm sure if you take your time and don't over heat the springs you will be OK.
    And it was my first time and it took about 4 hrs but should of taken only 2 hrs.
    But I played with different size spacers, instead of doing what was
    recommended. (just had to play)
    With the stock spring I had static sag of 33 mm and rider sag of 64 mm,
    with gear on.
    I cut 3 coils off at this point to bring the spring rate up from .42 to .455.
    And now I have a static sag of 33 mm and rider sag of 52 mm,
    unfortunately this was measured with out all my gear on.
    I did have to put a longer spacer in, I went from a 7.3 to 46 mm spacer.
    Now the rate that was recommended by Race Tech was .48.
    But we have found that sometimes the spring rate that you guys in the US
    like, are sometimes a bit to heavy for our riding conditions.
    So I will try this for a week or two before I cut any more off.
    The max I can cut off is 5.8 coils. (that is with 10% safety accounted for)
    And if I cut 5 coils or if you like 2 more, I will get the rate of .48.
    But as you can not put the coils back on, I will take it slowly.
    And will do it in two more steps so I don't over do it and have regrets.

    Here is a link with a good work sheet in it to help you out,
    #11
  12. meat popsicle

    meat popsicle Ignostic

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    Interesting link; I bet there is some good stuff in there.

    Just one OMFG: that fella in his review of a new DL650 took it up to 10,500 before he even got to 500 miles... now I know there are some people who believe in breaking them in hard, but JFK I had no idea they were wringing their lil' necks! :arg

    "there was a little metal in the oil" - no shite sherlock... it would be interesting to put that baby to bed one day - have two new engines blueprinted and then subjected to the two break-in theories (baby vs. biatch-slap) and then opened up and analyzed at what? 1000 miles? 5K? 10K?

    who would do this? mfg? mag? rich boy? :dunno
    #12
  13. Buckster

    Buckster Banned

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    So the fork re-valve is a case of inserting discs/washers into the fork tube? Sounds good.
    #13