GS500 Dual Sport Project

Discussion in 'Some Assembly Required' started by Bleached, Nov 1, 2011.

  1. FloridaSteve

    FloridaSteve Long timer

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    I "get" it and then i don't get it. For not insane dollars I can get a stock DR650 well within striking distance performance wise of a mild EX engine and for a lot less aggravation. But the cool factor IS off the charts though.

    #21
  2. dbarale

    dbarale Squiddly slow

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    Awesome but at $68,000 it is about $65,000 out of my price range... :lol3
    #22
  3. Chris S

    Chris S Been here awhile

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    Check out my what I call my 'GSR500' here.
    Been at it two and a half years, but only the back wheel and gearing to sort out now.

    DR front like you, but 19" Excels both ends like a flat tracker, so one spare does both. (I watched On Any Sunday at a vulnerable moment ;-)

    Have you heard of the SV650 shock trick? Get's the back up to match a DR front end.

    Good luck with your build. Looks like you're working it all out.

    There are some terrific machines in this SARequired section - my sorts of bikes!

    Chris S
    #23
  4. NortwestRider

    NortwestRider TRIPOD ADVENTURER !!

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    Is this the Chris S that wrote the book ???.
    #24
  5. Chris S

    Chris S Been here awhile

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    #25
  6. Adrian V

    Adrian V Been here awhile

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    Hi Chris,

    Just checked out the page on your GSR 500. Care to share the mods you did to press?

    Apologies for the thread drift Bleached, but it's sort of relevant....

    Cheers,

    Adrian
    #26
  7. Chris S

    Chris S Been here awhile

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    Hi Adrian, dont want to hijack either but what I listed above sums up the key mods:
    • DR front end
    • SV back shock
    • 19" rims on DR hubs
    The rest is (or soon will be) just the usual dirt road and travel mods + a platform to test stuff on.

    Chris
    #27
  8. buls4evr

    buls4evr No Marks....

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    How about a DR350 18" rear wheel and spacers in that GS? I know that a 350 wheel fits right into a DR650. This gives you a much better choice of OR tires. About the same circumference as the 17 with a bigger tire too.A lot cheaper than a DR650 wheel.
    #28
  9. pjm204

    pjm204 Long timer

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    Why not weld up the GS stem and then turn it down. I did this with good results on a KLR stem. If you're not comfortable with the welding, take it to a pro, I'm sure they won't charge much if you talk up your project.
    #29
  10. Adrian V

    Adrian V Been here awhile

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    Does anyone have a link on how to do the SV (650?) shock mod? Has anyone tried using the RMX or DRZ 400 forks/shocks?

    Cheers,

    Adran
    #30
  11. Chris S

    Chris S Been here awhile

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    Hi Adrain, the pic should be fairly self explanatory
    Top shock is standard
    Yellow shock is SV with a hole drilled an inch higher up the mount.
    Lifts it a couple of inches

    C

    Pic of near-finished bike here:

    Attached Files:

    #31
  12. Adrian V

    Adrian V Been here awhile

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    Thanks Chris, that's pretty clear.

    Does anyone know if any more radical alternatives have been tried? I'm wondering if given that the swing arm from the DR650 will fit, whether that gives additional alternatives for more suspension travel, perhaps from the DRZ400 or RMX 250?

    Just wondering, could be way off the mark here :1drink

    Cheers,

    Adrian
    #32
  13. Bleached

    Bleached Adventurer

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    this is great! good to know that someone else out there has taken this path and found the little 500 to be the right choice. I had planned on using the SV650 rear shock. I didn't realize that you have to drill it out, so that's very good to know. In addition to the lift, I think it also gets you about another 1.5" of travel.

    Since I think its pertinent here, and I'm curious, can you share the details of your front end swap? It looks like you used the earlier (Pre 95?)DR650, which from what I've found, should be pretty straight forward.

    To answer some other questions, I did think about welding material to the GS500 stem, but couldn't do that easily myself. In the end, I have the ability to have a new stem CNC'd pretty easily, so I'm taking that route. here is the model just for reference of the DR650 stem shortened for use in the GS500. we should find some time to get it turned in the next couple weeks. I have the actual solidworks file as well. If anyone needs it, PM me and I can email it over.

    [​IMG]

    Also, good to know on the DR350 rear wheel. I'm kind of looking at the rear, aside from the shock, as phase 2.

    A few thoughts on design of the stem: I purchased 12" of 1.25" 7075 T651 aluminum. It's a heat treated, stress relieved, high strength aluminum. The drawing shows it hollow, but I plan on leaving it solid. It's 17mm shorter in length than the original DR stem, and I'm using the same OD's as the DR650, so it theoretically should have a better column strength and be generally stronger. If anything, it's the neck of the frame that might experience an increased load.

    I'll get some pictures of the finished part once we're done.
    #33
  14. Bleached

    Bleached Adventurer

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    According to Rattonshaw, the first gen DR650 swing arm is a direct bolt up. Challenge is apparently with finding space for the shock.
    #34
  15. ohgood

    ohgood Long timer

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    oil cooler...
    new petcock...
    black paint (to hold the headers together)
    5 degree advance for fun..
    mind your goats and stalwarts syndromes...
    and hire a crane to pick it up...

    you should be set now !

    (subscribed, just for the mammaries) :D
    #35
  16. JamesG

    JamesG Rabid Poster

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    The SV shock is usually for the stiffer spring and (slightly) better damping.

    "Short" of a longer swingarm, you can increase ride height all the way up to the maximum extension allowed by chain clearance with shortened dogbones.
    #36
  17. Adrian V

    Adrian V Been here awhile

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    I'm curious what the effect of shortening or lengthening the dog bones might have on the rear suspension. I have a KTM 640 and have put different dogbones on to reduce the height a bit (short legs) and this has definately affected the feel of the suspension, as it feels harder initially and bottoms more easily. The concensus as to why this is occuring (if I recall correctly) seems to be that doing this affects the rising rate of the suspension for the worse. I also tried a greater reduction in ride height and the effect was more pronounced, with the shock bottoming way to easily. If anyone is interested I can probably find a link to a long thread about this.

    On a related note I think a longer swinging arm would give greater leverage on the shock, but this could probably be tuned out with a heavier spring and a re valve as the rising rate effect would not be compromised (I think).

    Anyone any other thoughts about this? At the end of the day I'm just wondering if a bit more travel could be gained and at the risk of offending the DR afficonados, as slightly better fork/shock be adapted to fit?

    That said though the DR/SV suspension certainly fits with the ethos of the bike and it's suited purpose, I'm just curious I suppose what's possible with the GS.

    Cheers,

    Adrian

    Cheers,

    Adrian
    #37
  18. JamesG

    JamesG Rabid Poster

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    Changing the dogbones changes the leverage ratios, or rather changes the relative position of the linkage which is connected to the spring, so its force isn't linear. Yeah its all very complicated geometry and some calculus, but luckily is not all that critical unless you are on a race track going 10:10ths. You just have to find a set up that gives you the results you are looking for and then accepting/get used to the resulting behaviors. When you go to a longer link (to lower the arm) is put the arm/shock further on the force curve acting like increased preload (sorta). Going the other way reduces it, which in this application is a good thing, you want softer to take advantage of the available travel, but its not perfect, and any change in suspension requires adjusting/changing everything else.
    #38
  19. Chris S

    Chris S Been here awhile

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    Actually it was a 2003 front end, and in great nick too. Late DR650s are not so common on the UK. We did the same as you: shortened and turned down the stem so the DR triple clamps and bearings fitted onto the GS headstock. To others: try and get a complete front end with wheel, disc, caliper and so on. Little bits like the speedo drive cost a fortune (could not find used, even on US ebay).

    I cant recall if we knew a DR650 swingarm would slot in, and if we did why we didn't do it. We've certainly talked about lengthening the GS swingarm (steel), but right now it looks like the 19" will fit.
    I dont know the exact shock space complications, but if you have a ready-assembled DR back end with wheel and brake with just the sprocket to line up, that could be less work than lining up the DR wheel/hub/brake in the GS arm (that's being done now).

    btw, I recall rattenshaw mentioning the pegs are too far back for easy standing and weighting - they are.
    It could be a major ergonomic issue, and moving it all forward is not so simple - is it?
    #39
  20. malokam

    malokam Been here awhile

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    I have a DR650 speedo drive laying around somewhere. If I can find it, pay shipping and its yours.:evil
    #40