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Progressive suspension upgrade

Discussion in 'The Garage' started by jigm400, May 21, 2011.

  1. jigm400

    jigm400 XS400 Enthusiast

    so cal
    i just installed new progressive fork springs on my XS this morning and let me say WOW:D it made a huge difference on fork bottoming and braking dive. With drewpy"s help on the OE specs i found progressive makes fork springs that will work in the XS400 even though they do not list an application.

    the OE fork springs are .4/.575 kg/mm

    progressive makes .54/.71 kg/mm (ps11-1115) and .63/.80 kg/mm (ps11-1109)

    i installed the .54/.71 because i found a set at work with 10 years of dust on them. just took the bike for a ride and could not make them bottom for the life of me. its huge.:thumbsup::thumbsup:
  2. drewpy

    drewpy Excess twin Top Contributor

    good to hear. Wurth make progressive springs, But I'm sure yours are cheaper :D
  3. Evan

    Evan XS400 Enthusiast

    I'm going to order new fork springs in the next couple days and I'm looking for some input. I weigh 220 lbs so I was going to order the heavier 11-1109. Am I on the right track or would that be too stiff? What weight of fork oil would you guys recommend and would you stick with the stock volume? Do you recommend buying them somewhere other than Amazon?
  4. drewpy

    drewpy Excess twin Top Contributor

    I stiffened mine up by filling the 20w oil to near the top (as mentioned in the Minton mods) makes it stiffer but great on the twisties.
  5. Evan

    Evan XS400 Enthusiast

    Is that Minton's recommended fork oil levels along with the springs I mentioned or without?
  6. drewpy

    drewpy Excess twin Top Contributor

    with the springs, oil can't compensate for saggy bottoms :D
  7. jigm400

    jigm400 XS400 Enthusiast

    so cal
    11-1115 are 22mm for the OD of the spring, the OD of the Forks are 34mm they work great for 150lb rider, as most of our springs are clapped out at this point in time (30 years or so)
  8. Greasey Fingers

    Greasey Fingers XS400 Guru Top Contributor

    If you stiffen up the front end, do you need to also stiffen up the rear suspension to balance everything out? Maybe if the fronts stiff but the backs sloppy it wont be all that nice handling?
  9. Vroom4

    Vroom4 XS400 Addict

    Did you ever install these? Im looking to get the same ones...:thumbsup:
  10. Evan

    Evan XS400 Enthusiast

    Unfortunately, no. I still have a shelf full of parts and 3 old bikes but no time to do anything with them. I'm hoping to get to them this summer though.
  11. last weekend i replaced the seals and springs in my 1980.

    was rather easy, except for getting the little round clip out and back in the top of the fork. that took some time and effort (without a vice).

    i added 15w fork oil and some generic seals i got at a local shop.

    these are the springs i ordered: http://www.amazon.com/gp/product/B000UK7MUG

    Progressive Suspension 11-1115

    they seem to work and fit really well! i installed them with the tight coils down. seemed to be easier to compress to get the top cap and clip back in.

    their website said it makes no difference what direction they go in, but tight coils down may reduce noise somehow.
  12. Vroom4

    Vroom4 XS400 Addict

    So I did actually do this... they work great! Maybe a little on the stiff side to be honest, but she holds the line so much better and braking is so much more controlled.
  13. Kosan181

    Kosan181 XS400 Enthusiast

    What are these ratings on the springs? I'm a 270 lb Rider (yes I'm trying to lose weight) what springs should I get?
  14. agent laraby

    agent laraby XS400 Enthusiast

    Ordering progressive springs at the moment so this thread has been really useful. Has anyone found or tried suitable emulators?
    Last edited: Mar 14, 2018
  15. franticvike

    franticvike XS400 Member

    Did you follow up on this? Planning to do my springs soon and curious.
  16. agent laraby

    agent laraby XS400 Enthusiast

    cooked the motor and now rebuilding so haven't done the upgrades yet

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