Heavier spring for 640 adventure?

Discussion in 'Thumpers' started by Converted Soul, Mar 29, 2005.

  1. Surly

    Surly surly adventurer

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    80 front and 260 rear?
    I might be interested once I verify what my 05 came with
    it seems too soft

    would you split the front/rear?
    #21
  2. G.Kennedy

    G.Kennedy ...

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    I think thats just a rear. 80-260 = 80 spring and 260mm length
    #22
  3. cugino pegaso

    cugino pegaso Been here awhile

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    80-260 is a rear only spring...

    8.0 kg/mm springrate
    260mm long
    #23
  4. rapiti

    rapiti IOR Veteran

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    Email sent.
    #24
  5. Stobie

    Stobie Mr. Motivated

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    I think this is the first time I've quoted myself.

    Anyway, 4mm makes a big difference. The 63mm ID of the PDS spring allows it to touch the shock reservoir. The options are to buy a WP, have Lowe's make a custom spring, or have a centering collar made that will center the spring.

    Hey, Cugino Pegaso, you sell that 8.0/260 yet? :ear
    #25
  6. BlitzBike

    BlitzBike LC4 Pilot

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    Hey, how about some springs for us BIG boys? I weigh 285 down from 300 and the race tech guys don't even list anything CLOSE to my tonnage. And I got panniers too!

    Anybody know any supension GURUS for big guys--- especially on the EAST COAST?
    #26
  7. Stobie

    Stobie Mr. Motivated

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    Sourcing the springs from Lowe's Racing didn't work out as I expected. Fortunately, they are easy to do business with once you get hold of them, and the exchanges/returns were painless.

    It turns out that the 4860 forks on the Adventure use 485mm long springs, while on the RFS bikes they are around 510mm, even though all the online applications lists I've looked at list the 510mm's as being for ALL 4860's. I didn't know this till I disassembled my forks. Brad is cutting down and grinding one of his longer sets to fit my forks, targetting the .48 to .50 range. There aren't enough preload spacers in there to be able to remove enough of them to run the longer springs without having way too much preload.

    Brad mentioned that he was having a bunch of 485mm fork springs made in .48 kg/mm and .50 kg/mm rates for somebody on the West Coast. Anybody needing springs in these weights might want to give him a call. You heavier 950 guys may even want some .52's.

    They can have made anything you want, I believe for $125-$150 per set of fork springs, or rear shock spring. The lead time could be the killer.

    Yall be cool.
    #27
  8. ozadvntr

    ozadvntr Planning that trip, again

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    I found the front end terribly soft on my 05 640. I replaced the stock springs with 0.48 springs and the change was dramatic. It lost the dive that the twin Disc exhibits. Don't get me wrong, it still dives, but not as much. It seems a better balance when ful of fuel as well.

    Mick
    #28
  9. ktmnate

    ktmnate Long timer

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    I went with a .50 in the front and it's awsome. For the rear I just don't remember and my bike is at home now. However I think it's a 8.0 somehting... It was done by Dick's racing in Citrus Heights 916-722-2373. I had him re-spring and re-valve the whole thing. I took my forks and shock and picked them up a week later.
    #29
  10. nosedive

    nosedive Been here awhile

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    #30
  11. AndyB

    AndyB Lonely Traveler

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    on my 02 Adv, had my fork revalved and sprung with 50's & shock no valve work, but new #80 spring($340.oo).
    Along with jetting/airbox sidecover/carb mod, is THE best improvemnt one can do to the 640Adv(my opinion).
    i ride the big bike pretty agressive('cause ya can't ride slow and pokin on such a big bike, gotta keep all that wieght moving or they tend to fall over and squish ya),in tight woods of WV/O/KY=steep,rocks and big water bars, Yet with a few clicks of comp/rebound on the shock adjustment, ride is smooth on casual cruising back road rides too. i can't imajine riding loaded on a long tour without stiffening things up, esp. if ya wiegh 190lb. or more...... if you're thinking of re vamping your susp., i highly reccomend them. ....AndyB
    #31
  12. Velocibiker

    Velocibiker Adventure Antagonist

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    I've heard this so many times I've just got to ask;

    Exactly what do you mean by the above. Are you saying the suspension is only good if you weigh 165lbs?

    I know it says in the manual that the factory shock setting is for 75kg.....

    BUT...............

    it also states that if you weigh more or plan on adding luggage or a passenger, to change the spring preload.


    So - That tells me that the factory setting is for 75kg. Not that the spring (properly adjusted) can't or isn't OK for somebody heavier. AFAIK, if you can get the correct sag settings, the spring is fine.

    I think your statement (and the others who tout it) is misleading and incorrect. I think a more accurate statement would be that the OE spring is fine if you weigh between XX and XX.

    I admit I don't know what the max weight capabilities of the OE spring are. But that would be easy enough to determine if somebody was so inclined. I'm not, I'm happy with it the way it is (stock - properly adjusted). I bet WP might even know that already.

    Anyway.....

    Sorry about the (semi) rant, I've just wanted to make this point for a while.....

    Nothin' personal. Just happened to be you (this time) Meat :D
    #32
  13. meat popsicle

    meat popsicle Ignostic

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    No problem here velo; you got all your ducks in a row. Very reasonable detail to the story you are adding. :thumb

    I just might add that rider preference for suspension response might figure into the mix of which spring for a given rider weight (with gear) and, as you point out, the recommended sag measurements.
    #33
  14. numbaphive

    numbaphive not quite rite

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    Even I'm confused and I know how to do this!

    As a rule on an mx bike your race sag (you on bike) should be approx 1/3 of your suspension travel i.e. suspension travel = 300mm, race sag = 100mm.
    This allows your suspension to work within design parameters and is important to the way the bike handles.

    Due to the dual sport nature of my bike I run 1/4 of suspension travel which is about 75mm. This is not law as some people like it soft in the rear and some folks like it hard so there is room to accommodate personal wants and needs. If you weigh more than your springs rating or you constantly carry a passenger or luggage I would suggest getting a heavier spring or increase the spring pre-load. If you shorten the spring(turn collar nut clockwise) you increase pre-load.

    4 the metrically challenged 1stone = 6.5kg, 1in = 25.4mm

    Hope this helps.

    #34
  15. meat popsicle

    meat popsicle Ignostic

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    #35
  16. overlandr

    overlandr Dystopist

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    Hey Buckster, how did you go with that 80/250mm spring of yours? Does it bottom out or are there any other dramas/limitations using a spring 10mm shorter than the specc'd one? Less sag adjustment for luggage I suppose? Don't you just love waking up these old threads?:D
    #36
  17. Mifune

    Mifune Been here awhile

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    After reading through a lot of part lists and catalogues, I believe the following springs to be alternatives, all of which are 43mm x 485mm for WP 48mm forks, that will fit a 2003 - 2007 640 Adventure:

    Part No. Description Original Application(s) Notes/exceptions
    91410006S 4.4N/mm 640 Adv (2003 - 2004)

    91410019S 4.6N/mm 640 Adv (2005 - 2007)
    990R Adv (2007 - 2010)

    91410020S 4.8N/mm 990R Adv (2007 - 2010)
    950 Adv (2003 - 2004)

    91410021S 5.0N/mm 690R (2009 - 2011)
    990R Adv (2007 - 2010)
    950S Adv (2003 - 2004)

    91410010S 5.2N/mm 690R (2009 - 2011)

    91410065S 5.4N/mm 690R (2009 - 2011) 465mm length

    I'm sure there are others and it would be useful if we could keep a list of substitutions people have used with success and others we've had trouble with.

    -Stuart
    #37
  18. Shlomc

    Shlomc n00b

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    very long time since someone have dealt with this stuff but, hope to find some answers for some dead ends...

    my 2006 640adv suffers from abnormal front sag. (45mm static, 58mm rider's, preload 35mm, spring lenght 460mm, 5W oil air chamber 120mm). so i wonder why dont replace the shi##y springs?
    rear sag is OK. my weight is 83kg (183lbs)without riding gear, riding solo.

    looking for replacement springs raised some questions..
    1.progressive or linear?
    2. if linear - 4.8 n\mm is the recommendation (from digging ADV threads)
    i found this dealer who sell springs to the above specs, although he specified that springs diameter is 43mm, and the KTM 2006 serial parts manual says 51mm diameter.. (http://slavensracing.com/shop/fork-springs-wp48mm-43mm-x-485mm-for-ktm-husaberg-wp/)
    are these dimensions are for different measures of the springs?
    3. i have an option to install new 4.8 n\mm springs from a 990 (again different diameter -5.25 mm) will it feet? are there any differences i should consider before making my mind?

    thanks a lot for helping.

    s.
    #38