Fork midvalve question- and other DIY suspension tuning

Discussion in 'Dakar champion (950/990)' started by slackmeyer, Sep 5, 2011.

  1. Torque

    Torque Been here awhile

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    The shock or the shock spring? The shock can be made to do anything you want it to do. From wondering to full professional racing. Way better than the 1090R 790R the current EXC models and the aftermarket.
    All pds needs a bit more progression and that is why they benefit from a correct variable rate. This also allows larger range of single up and two up performance.
    The shock is too firm in initial stroke from the factory and that is a combined valving, spring issue. Traction and compliance suffers. So we open it up initial and slow it down deeper into the stroke.
  2. Zuber

    Zuber Zoob Supporter

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    Of course the spring sets the load. Then the shock damping has to be set to match.

    So, you give the shock less initial compression before the cross over? Maybe add a cross over (haven't looked at the chart recently).

    Slowing it down deeper in the stroke is in the stack after the cross over, OR are you talking about the second piston of the PDS?

    @Torque , your posts in here are excellent by the way.

    Edit addition - if I'm riding in a very narrow type of terrain and loads, no jumps, moderate size bumps and a lot of small wash board and small hack. Do I really need a more progressive spring? Since I won't be taxing it to the extremes?
  3. Torque

    Torque Been here awhile

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    I do a Xover early and hit the brakes after that with shims. Secondary bottoming piston a bit more but also the high speed compression is valved.
    If you have a straight rate spring with a lighter than average pre-load then you can get good performance in the beginning of the stroke which is what you are looking for.
    Don't forget rebound. Gotta get your tire back to the ground and it is a bit heavy in the rebound at certain speeds.
    Gotta boast for my rider Noah. He just took a 3rd in pro II at the Worcs race right behind Andrew Short. He just texted "your the man" I just beat the points leader two weekends in a row. He is more of a hard enduro guy not the high speed stuff.
    His bike, Linkage 2020 Husky with variable rate spring. The only variable linkage in the field and will be the only one at the next endurocross. Believe me if the spring is correctly made it works!
    Dusty likes this.
  4. uk_mouse

    uk_mouse Aquatic adventurer

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    Hey Torque, can you supply me a progressive shock spring and shim kit suited to my weight and riding? There doesn't seem to be much knowledge here in the UK about the suspension on these bikes, no one I've talked to locally is very interested in helping me. I got fork springs from Konflict, very happy with those but their full solution was very pricey, so I bought shims and followed the excellent advice in this thread. I'd rather buy the parts if I can and try and do it myself. Thanks.
  5. bobone

    bobone Been here awhile

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    i understand... but that's too many pennyes for me... :D
  6. bobone

    bobone Been here awhile

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    maybe we can share the postage and the customs? form the us it adds up quiclky...
  7. LocuL

    LocuL Gnarly Infantry

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    Is it 265 or custom custom...300mm is my dream
  8. Whodatschrome

    Whodatschrome Long timer

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    Hey @Torque, that was a good move on finally changing your avatar picture to something that helps represent you a bit better. Now we all know that you ain't some armchair quarterback throwing out random suspension wisdom tidbits.
    Torque likes this.
  9. opanos

    opanos Been here awhile

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    Any suggestions for front springs, mainy for road use? Every local dealer strongly disencourages me from +0.60kg/mm springs
  10. Torque

    Torque Been here awhile

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    How much do you weigh?
    I am an off road specialist but the super moto bikes run really stiff springs and valving to keep the front end from diving. .60kg is mush on that bike unless you are very light. Some like mush on the road though.
  11. 1coolbanana

    1coolbanana Long timer

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    Its 265, spaced for 250, same as the front :-)
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  12. 1coolbanana

    1coolbanana Long timer

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    Me too :(
  13. LocuL

    LocuL Gnarly Infantry

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    But thats only SE country. What human can live with such small stroke...
  14. 1coolbanana

    1coolbanana Long timer

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    More that enough for my tired old body :gerg
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  15. opanos

    opanos Been here awhile

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    Approx. 100kg. Road use 90% of the time. I have an S model, thus full factory suspension. For now forks seem to suffer most, as it dives to much and gives me back a vague feeling of the road. Will I need progressive or linear springs? Revalving after new springs are installed is required? And what about the rear shock? For now it feels at least decent
  16. Torque

    Torque Been here awhile

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    Forks nearly always need linear springs. Forks are too progressive. S model needs less spring due to more travel. Just mentioned in a PM the 790R comes with .68kg springs and weighs 50lbs less than the 990. Same forks you have just less valving on the right fork as the Xplor right fork is gutted of most of the valving components.
    Mostly road with moderate riding I would go to about .66 with about 10mm of initial pre-load. Shorter than stock spring or you will have 17mm of preload and that will create harsh initial hit. light pre-load will be more plush in initial hit than you currently are experiencing. The black plastic spring guide that the spring slides over will have to be ground, filed, or turned down so the spring can slide over it and you are in the game. I have checked and noted the pre-load on some of the 990s and came up with 17mm but I have not checked all of them as I dive in and make them proper anyhow. So I could be off about the 17mm on your particular bike. .66kg would be on the soft side for your weight if we were dialing you in for off road.
    Valving maybe yes, maybe no, you have to ride it and see if your improvement is adequate. Be assured it will be a noticeable improvement with just springs.
    mountaincadre, opanos and Dusty like this.
  17. opanos

    opanos Been here awhile

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    Hi!
    Thanks for the response!
    Where can I find these springs you are referring to? And how can I select the lenght of these springs? Usually spring lenght is prefix, and I definitely don't want to ''hack'' them.
    You believe that I should't do anything on the rear shock? It has been serviced recently but the spring is fully preloaded for a decent 40% sag. But still it feels quite ok
  18. uk_mouse

    uk_mouse Aquatic adventurer

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    I got fork springs from Konflict, and I've just ordered a new progressive shock spring from Mr Torque. Both in the US, so postage / customs is a cost we have to bear here in Europe. But the suspension knowledge for these bikes really seems to be concentrated in the US.

    I also have an S model, I agree about the dive, it was terrible. When riding 2 up my wife would regularly "peck" me on the back of the head! What I did was fit 0.62 fork springs from Konflict and use the "johnf3" valving described in this thread. The difference is amazing, no more dive, no more pecking, and the off road handling is loads better.

    However, having spoken with George at suspension101.com (posting here as Torque), his opinion is that I should have gone even stiffer on the fork springs. And I can't fault his logic, as he points out, the 790 is supplied from the factory with 0.68s, and it's a lighter bike. But I'm sticking with it for now, mainly for financial reasons!
  19. bobone

    bobone Been here awhile

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    do you know the details of the shock spring? how much was the total with customs and shipping?
  20. bobone

    bobone Been here awhile

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    how... with no preload i have 50mm (25%) sag. how can you have 40% at full preload?