640 Adventure fork springs

Discussion in 'Thumpers' started by R&R4adv, Jun 9, 2007.

  1. R&R4adv

    R&R4adv Been here awhile

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    I have picked up some 48mm x .48 wp fork springs for the 640 but they are the 510mm long ones for i think exc or sx will these fit my 03 640 adventure.
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  2. Twotaildog

    Twotaildog Old Poop

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    If anybody can clarify the whole 640 adv fork spring thing, I also would appreciate it. Mine's a 2001 and I can't seem to find springs anywhere. I'd like to find some .49's. I'm told the 2001's had 48mm WP "Rallye" forks which are apparently different than the "non-rallye" 48mm forks used in subsequent years. Neither Race Tech nor KTM have been able to supply me with springs. Today I will pull a spring and measure it to call Race Tech and see if they can match it up. Other than that, can anyone clarify what years/models are interchangeable and/or tell me who can supply springs for this thing?

    Much appreciated...
    #2
  3. boyscout

    boyscout sittin' down

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    I've been figuring out my suspension as well. Seems there's a lot of conflicting info around. When I first went into the dealer their book suggested I had 43mm forks (2002 Adventure R) but I was pretty sure they were 48's. I ended up pulling a spring and giving it to them to measure. It's a 48. I've got it out in the garage so I'll measure it and let you know the dimensions.

    When they measured it, they said it was the same spring they are using in the current 950's (not sure whether S or not) so I'm pretty sure if you have the same fork I do you can at least get 48's from KTM. That's probably what I am going with.

    Perhaps we need a thread to start collecting this data in one place.
    #3
  4. halfcab

    halfcab Been here awhile

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    My 01 is an LC4-E with the 43mm WP forks, I "believe" the odd ball size were 50mm in 99.

    I know for sure the stock springs that came in my 06 450 EXC (48mm) will not fit in my 43mm, there two large. I was making an 8mm shim for preload and thought I give it a try.

    The front springs are easy, the rear spring is the one that I'm finding hard to find.
    #4
  5. boyscout

    boyscout sittin' down

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    Here's my spring info:

    2002 LC4 AdventureR 765mm length, 43mm OD

    Check the Index, there's a suspension thread which mentions a place called Connor's (I think, can't find the thread right now) that will custom wind a spring for you. I called them up and it was around $130 bucks.
    #5
  6. Twotaildog

    Twotaildog Old Poop

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    Ya, the Enduro has whole different forks and shocks than the Adventure. '01 Adventure has 48mm forks and the shock is a different unit because the Adventure has linkage whereas the Enduro shock is hooked directly to the swingarm. Suspension wise, I believe not much will interchange between the two.
    #6
  7. Dotbond

    Dotbond Africa, Africa

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    And my 04 Enduro has linkages on the rear shock like the Adventure.
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  8. Luke

    Luke GPoET&P

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    They'll fit, but you'll really have to cram them in there.

    The stock adv spring (for the 48mm WP USD forks) is 43mm x <strike>480mm</strike> 485mm (edit). mx-tech sells 43mm x 495mm springs (linky) which I have in mine. It took a bit of a squeeze to get them in, but they work. There are also some spacers in the forks which I will remove soon to get the front end sag right. The 510mm springs may have too much preload to work right.

    It is possible to cut the springs down if you find that they are too long- this will increase the spring rate slightly as well.
    #8
  9. Luke

    Luke GPoET&P

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    Yeah, like my owner's manual that says I have 43mm forks and my calipers that say I have 48s. The '02 forks are apparently yet another mid-year change. Out of curiosity, does your bike have the oil-filter-relief frame casting? My '02 and a friend's '02 both have the casting, and also both have 48mm forks.


    For reference, the model number for the '02.5 and '03 forks is WP4860. These forks (with varying springs, shims, and valves) are used in several models of bikes. KTM LC4s, RFSs and Husabergs, that I know of.
    #9
  10. R&R4adv

    R&R4adv Been here awhile

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    It looks like i may be able to use the 510 springs, I'd really like to hear from someone who has done this.
    #10
  11. boyscout

    boyscout sittin' down

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    Yep, I guess I have a 2002.5. :thumb
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  12. bmwktmbill

    bmwktmbill Traveler

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    Dont confuse the diameter of the forks with the diameter of the fork springs. It is my understanding that a 4860 fork has a 48mm tube so this number does not speak to the spring diameter.

    On my '02 Adenture I shortened the fork 2 inches to lower the bike. that entailed a travel limiter piece internally and cutting the spring 2 inches shorter. Stock the rate was .44 but cut two inces shorter it became a .49. This rate change was measured by Canonracecraft. They can cut your springs or wind you new ones. You can do it yourself too. I did.
    hack em, heat em flatten the coil and grind the coil flat. An Oxy-act heating tip cuts and bends them fast.

    The preload caps on the adjustable models allow a 10mm variability plus you can preload the springs internally with spacers on the non adjustable caps.

    I know you guys are concerned about spring rates but you are wrong in my opinion to place all the responsibility for how the fork works or doesn't on the rate. Actually the damping and the airspring are much more important in how things feel/work up front...and in the rear.

    Honestly I don't think you will solve the problems without a revalve and subtanks up front and a revalve in the rear.
    Z dog has published the correct shims to use for a revalve upfront and will do our rear shock for resonable money and he can help you with spring selection. He knows the vendors.
    http://www.infinitymachineanddesign.com/Contact.htm

    Drop the cash and be done with it.
    Throw in a scott's steering stabilizer....
    The results will blow your mind.

    I hit a gut pile on I-5 the other night. The bike never even moved out of line.
    Bup-bup and I was over it at 65 mph.
    It's a saftey issue and your ass is on the line.
    b.
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  13. Luke

    Luke GPoET&P

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    This guy here had some 510 springs and returned them, but it doesn't seem that he actually tried them.

    If your springs are new, I'd sell them and put the money towards new springs. If they've already been used, you have nothing to lose by trying them out. Just install them. The suspension should sag a little with just the weight of the bike on it. If the forks stay topped out, then there is too much preload.
    #13
  14. Twotaildog

    Twotaildog Old Poop

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    Race Tech told us today that they have springs that measure 508mm long and are the same diameter as my stock springs. My stock springs are 485mm long, so the new ones will be 23mm longer than the originals. With the original springs, my forks had 18mm worth of spacers. It seems do-able. Worst case, I have to shorten the new springs, but I'm thinking they'll probably be close enough as-is. I'm going to give it a try.
    #14
  15. R&R4adv

    R&R4adv Been here awhile

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    Kevin, I'd be glad to hear how you go, I have no problems shorting the 510mm long springs if i have to but it would be easyer if i didn't.

    Reon
    #15
  16. Twotaildog

    Twotaildog Old Poop

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    I'll let you know how it goes.
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  17. Zerodog

    Zerodog Long timer

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    Yes you can run the 510mm springs. You just need to remove all of the preload spacers except 1 of the thinest ones. I think all of the inverted forks on adventures are 48mm forks. Depending on how much you weigh they might work very well. I would try them out before you go and cut them up.
    #17
  18. Twotaildog

    Twotaildog Old Poop

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    That's the plan Z
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  19. clintnz

    clintnz Trans-Global Chook Chaser

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    Munn's online parts listings are an easy way to compare what bits cross over between KTM models - just look for the part numbers. There were a few changes back & forth between 43 & 48mm on the 640A

    & All LC4's have a linkage rear suspension.

    Cheers
    Clint
    #19
  20. Twotaildog

    Twotaildog Old Poop

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    you're right about that. I was mistaken. Don't know what I was thinking.
    #20