Yamaha forks on a BMW F650GS Dakar

Discussion in 'Thumpers' started by skibum_1260, Oct 23, 2008.

  1. WayneC

    WayneC Long timer

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    Any of the WP4357's are fine, there is more info out there re parts, manuals and valving than the YZ, the TT WP forks and how they did the kit is also a good guide. The airhead guys are using the info I put on line for their conversions
  2. dready bear

    dready bear Been here awhile

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    Cheers,
    It looks like the LC4 ones I have found might be supermoto, so yolks are too wide.
    I see from you site you can use ktm 250 forks (WP4357), are they the same firks then as they use on the larger bikes?
    This is all so confusing :( I have found a pair of brand new YZ 125-250 firks, no yokes, for £75.
    Everyone says they are easier to fit, but why?
    It looks to me that its easier turning down the head rude and using ktm f wheel, brakes than it it is getting someone to make a brake hanger, axcel ECT you would need on the yz forks. I would use BMW f wheels as the I still want a larg disk up front.
    As I say I'm well confused
  3. WayneC

    WayneC Long timer

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    There are two series of open chamber WP forks on the early KTM's, 4357 and 4860, the info on my web site shows what model each of the fork types are used on, yes you can use the KTM wheel, with brakes you use the BMW caliper as KTM use Brembo like BMW and the hanger is over the counter from KTM, the hanger from the KTM 950 is for a 300 mm disc and Brembo caliper

    The YZ is easier as the yokes bolt straight on because the outer diameter of the SHB is the same as the GS
  4. dready bear

    dready bear Been here awhile

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    Ok thank you,
    In your honest opinion what forks would you go for?
  5. WayneC

    WayneC Long timer

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    The YZ forks are easier to fit, WP takes more engineering as there are not simple kits out there

    It comes down to price of the available parts and skills/workshop availability, dont go into something you cant complete safely
  6. dready bear

    dready bear Been here awhile

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    I'm leaning towards WP as there cheaper here, plus im lucky enough to have access to a £23million workshop :D so the engineering side shouldn't be a problem :D
  7. WayneC

    WayneC Long timer

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    Well the spreadsheet and pdf's I have online have all the info you need for the WP forks, valving for the GS is in there
  8. dready bear

    dready bear Been here awhile

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    will any of these forks fit f650gs

    cr
    crf
    aprilia rxv
    suzuki drz

    cheers
  9. dansin

    dansin Been here awhile

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    You can make almost anything fit and with the workshop at your disposal, it should be easier than for most others. It's just that most folks have gone down the tried and tested YZ or WP route.

    A quick scan of eBay:-

    Yz250f top clamp £22, free post

    http://www.ebay.co.uk/itm/YAMAHA-YZ...44?pt=UK_Motorcycle_Parts&hash=item4177acdb2c

    Bottom clamp £25, free post

    http://www.ebay.co.uk/itm/YAMAHA-YZ...55?pt=UK_Motorcycle_Parts&hash=item4177ddf96f
  10. WayneC

    WayneC Long timer

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    Re Disabling ABS on the Sertao for those doing a fork swap and getting the speedo to work

    The rear wheel sensor needs to be extended to Dash Connector Pin3 (SEH+ Ws/Sw) and Pin 17 (SEHS Ws/Br)
    These two pins are unused in the ABS Vsn wiring but used on a non ABS machine so the dash handles both signal types

    Dont know about the ABS lamp ........yet. Would be worth checking the Dash P/N is the same for ABS/Non ABS Models
  11. dready bear

    dready bear Been here awhile

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    Right, I have just bought a pair of white power forks to fit to my F650GS Dakar.
    They are off a 2005 Ccm 644 DS.

    But what model are they??? as i need to order new springs, yokes ect

    I'm sure they are 48mm but bar that I have searched and searched but cant find anything :( i thought they were going to be WP 4357 or WP 4860, but i cant see them number anywhere :(
    [​IMG]
    The top cap numbers on each are
    42.02
    0502W713
    [​IMG]
    the lower numbers are different,
    no disk side
    01 (in a sun thing)
    2886
    disk side
    02 (in a sun thing)
    2885
    [​IMG]
    on the inside of the fork guards it has KTM stamped inn
    [​IMG]

    all this means nothing to me so can anyone help?
    Will
  12. WayneC

    WayneC Long timer

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  13. dready bear

    dready bear Been here awhile

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  14. WayneC

    WayneC Long timer

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    Yes it does, you will need to start looking a little more closely at details if you are going to get anywhere with it. 4357 = 43 mm 57 mm, 4860 48 mm 60 mm
  15. dready bear

    dready bear Been here awhile

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    oops im sorry to offend :cry , i take it they are 4357 then, i just never clicked that it wasn't just the part number but the fork dimensions. everyone just said the number are stamped on them, which there not
  16. WayneC

    WayneC Long timer

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    Dready Bear, Measure the lower fork tube diameter to determine the type, the next step is to measure the length from axle centre to the top of the forks and compare that to the lengths in the WP Notes pdf I have online, that will tell you how much they need to be shortened to suit the GS and that will tell you the length of spring you will need. It looks like the for on the forks is for a 20mm axle, check it.

    Since the forks are set up for the CCM 644 you will not know what rate the springs fitted are, it is likely they are around 0.46, the spring rate can be determined from a spring rate calculator like the one I have online. The valving will also be unknown and that will need to be checked and possibly adjusted, again that is all in the WP Notes pdf

    If they are 4357 then you will need to buy a set of KTM yokes from an MX 250 or 450 with at least 20mm offset
  17. GSBS

    GSBS FunHog

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  18. Linusp3

    Linusp3 Been here awhile

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    I intend to do the YFZ front end switch and keep the stock wheel and brakes.

    How did you guys solve the ABS-mounting bracket?
  19. hasenwerk

    hasenwerk Long timer

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    I currently have some YZ250F Forks and triple for my non-ABS 2006 650 GS. I have found locally, but have not bought an Excel 21" wheel, axle and caliper from a YZ250F for about $150, but there is no disc or spacers included.

    On fleaBay, a 270mm YZ kit, delivered is about $150, 320mm is $225 delivered.

    So... bang for the buck here... is it worth it to spend $300 / $375 on the Yamaha parts or should I just get the parts for using my BMW wheel and caliper instead? What is the current costing and source on the parts that allow you to use the BMW wheel and brakes?

    One thing I may consider is installing the YZ suspension on my 2013 Sertao and transferring those parts over to my GS seeing how I have a Dakar rear shock on it... then it might be worth the specialty machined parts...

    I would like some "real world" comparisons on the difference between BMW braking and the 270 and 320mm Yamaha brakes. I find this all funny as my 900kg Volkswagen Jetta has two 239mm discs and it stops fine!

    Decisions decisions...
  20. dansin

    dansin Been here awhile

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    My bike is with a suspension guy who is going to revalve the forks and possibly sort out the rear shock. I'm currently running 1" raising links in the rear which will get changed back to the standard links when I get an 18" rear laced. Do I need to get the forks shortened as well (possibly the 25mm as per what HOH do) to match an 18" rear? Does that 25mm reduction in height of the forks take into account different height of the spacers (I think mines 12mm) under the top clamp?