An Unholy Union II: Wp Extreme 50mm Conventionals on a G/S

Discussion in 'Airheads' started by Solo Lobo, Apr 9, 2011.

  1. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
  2. Solo Lobo

    Solo Lobo airhead or nothing

    Joined:
    Mar 16, 2004
    Oddometer:
    9,926
    Location:
    Shoreline, WA
    Thanks for the bump Jenna,

    Looks like the custom R-Dubb/HPMGuy triples will ship soon... all other parts are in-hand, with the exception of some brackets I need to fab to hang the stock headlight unit on the new triples....

    That being said, if it looks like I may get this other '81 G/S this project will go on hold.... the WP front end would go on this other bike and my current one would go up for sale.
  3. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
  4. Solo Lobo

    Solo Lobo airhead or nothing

    Joined:
    Mar 16, 2004
    Oddometer:
    9,926
    Location:
    Shoreline, WA
    I've bought four sets in the last couple of years and the most I paid was $200 for the forks I have now, with triples and a fork brace....
  5. ontic

    ontic

    Joined:
    Jul 14, 2008
    Oddometer:
    1,324
    Location:
    Melbourne
    You guys have got it good over there,
    here's some forks for $100 buy it now, no triple or anything else though, and they look a bit faded but...? . I think I stumbled across them almost a week ago (they wouldn't last that long at that price on aus ebay).
    pt=Motorcycles_Parts_Accessories&hash=item35b3404fbd#ht_500wt_956
    here is another grubby set for a little bit more


    I've seen a few others at that price as well.
    I got lucky with mine when a adv member replied to my wanted post with a very fair price, but eventually i would like to get another set for spares- I've been looking and chances are few.

    Talking about a fork brace- let me know if you come across one, I want one:deal. This was an interesting one I hadn't seen before on german ebay (no international shipping)
  6. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
    I don't know why I did it but I just bought a set for a 100bucks from a 99 125 sx. triples included with shipping! I felt like I couldn't pass it up. Have no idea what axel to buy or wheel? I mean can we run a wheel from a 125 without bending the holy shit out of it?
  7. Castironmeyer

    Castironmeyer Adventurer

    Joined:
    Oct 21, 2008
    Oddometer:
    59
    Location:
    Indiana
    Great thread :D, would like to do this mod this winter
  8. bgoodsoil

    bgoodsoil Dare to be Stupid

    Joined:
    Jul 9, 2008
    Oddometer:
    4,687
    Location:
    Washington, DC, USA
    KTM increased the axle size on the WP4860. I want to say in 2003 but I'm not sure. You'll need to make sure and get an axle and front wheel off one of the older style.

    AW, you listening? Do you know which year they swtiched?
  9. igormortis

    igormortis Cafe Reise

    Joined:
    Dec 22, 2006
    Oddometer:
    1,602
    Location:
    London
    I think it was 2002-03 from what I remember. Pretty easy to spot the larger axle size from pics once you’ve seen a few. I think mine are stamped late ’02.

    It also looks to me like the GS axle can be made to work with these without too much effort. Which may also mean that the KTM axle could be turned down slightly to suit the BMW wheel bearings..? I haven’t seen the KTM unit though, and haven’t compared dimensions, so I can’t yet comment with any authority!
  10. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,926
    Location:
    Back in Seattle, FINALLY
    Yeah it was 2003 that the 4860s went from a 20mm to a 26mm. I have no clue what the 4357s before them or the 50mm even earlier used. No clue. My suspicions would say it's the same 20mm, but that'd warrant some checking.
  11. Solo Lobo

    Solo Lobo airhead or nothing

    Joined:
    Mar 16, 2004
    Oddometer:
    9,926
    Location:
    Shoreline, WA
    These 50mm's take a 17mm axle, and I think all KTM axles are 17mm from 1997 to 1999 at least (check the parts diagrams)

    The wheels carry the same part number for all 17mm years, so yes Jenna, you can run a 125 wheel (same as the 640 wheel)

    The trick is to find out how to get the largest diameter brake rotor, which I think roadsacallin' did on is 250cc forks.... check the german company HE for more options as well
  12. ontic

    ontic

    Joined:
    Jul 14, 2008
    Oddometer:
    1,324
    Location:
    Melbourne

    Yep, and the trick to big rotors depends on your fork leg (as i have learned the hard way) and what rotor size you want to go with. It is a bit confusing. As I am pretty sure Solo had already explained, forks from smaller bikes have different lugs than the forks from the 640 (and possibly more). This means you need different adapters. HE still makes the adapters (not cheap) and if you watch german ebay enough you can find them second hand. They make a one piece adapter that replaces the entire caliper holder and moves from a 300mm to a 320mm rotor, and they make a caliper adapter that moves the stock caliper holder and caliper out to move from a 260 to a 320mm rotor. They might make more- I am not sure.
    here is their address which was a bit difficult for me to find
    http://www.he-motorradtechnik.de/

    Here are the 300mm ready forks (Solo's)
    [​IMG]

    and (ignoring the 'incorect' caliper bracket that is bolted on and the 320mm rotor), here are the 260mm ready forks (mine), notice the different lugs,
    [​IMG]

    here is an old HE adapter to move from 300 to 320mm (wouldn't fit my forks but would fit Solo's)
    [​IMG]
    HE sell this for 75,63 €
    KTMax sell it for 105,50 €
    http://www.ktmax.de/show_product.php?products_id=244

    Here is a set of forks with the different lower fork lugs (like mine) and the caliper adapter that moves the stock caliper holder out to go from 260 to 320
    [​IMG]
    [​IMG]
    HE still sell this part (not sure of price yet).
    KTMax also sells this 105,50 €
    http://www.ktmax.de/show_product.php?products_id=243&SESS=fc1a7f4a6d7f7e5d1b68e11843390188

    I didn't get any stock caliper adapter with the parts I built my front end from, and having gathered two caliper brackets for later USD forks (one for 320mm one for ???mm) I've cobbled them together and have gone a very odd way towards fitting a 320mm rotor.:lol3
    so far I have about $30-40 in these brackets
    (still in mock-up phase)
    [​IMG]

    [​IMG]

    If I can find a stock caliper holder for these forks for next to nothing then I might get the correct HE extender bracket, we'll see. My 'solution' has sort of grown on me.
  13. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
    So doing some research right now with bearing sizes. And it seems that DR650 races and KTM bearings may get along with no machining of the stem. I'm talking to a few people who have done an extreme swap on their dr's. The dr races fit in our headstock almost perfectly. There is a slight recession on the bottom race but it doesn't keep the bearing from seating. This may be a cheap alternative to machining as long as you don't mind a few spacers. As soon as I have some concrete measurements I'll post them here.
  14. Solo Lobo

    Solo Lobo airhead or nothing

    Joined:
    Mar 16, 2004
    Oddometer:
    9,926
    Location:
    Shoreline, WA
    So, what you are saying is that the DR bearings have the same OD as the BMW bearings and ID as the KTM nearings?

    What are the DR's bearing numbers? There is a site I can pull the specs on 'em (If I can find it again)

    The BMW stem diameter is 28mm
    The KTM stem diameter is 29mm

    and I thought the DR650's was 30mm??

    [​IMG]
  15. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
    Hey Solo, please keep in mind that I'm a bit of a dumb ass. Here is the response I got from an inmate with extremes on a dr:

    The bearings are very close but not a perfect fit. KTM stem is about 1mm longer I think. I don't remember the details but you will find them in these threads:

    http://www.advrider.com/forums/showthread.php?t=646076
    http://www.advrider.com/forums/showthread.php?t=712386
    http://www.advrider.com/forums/showthread.php?t=461806

    I'm at work and cannot find the site with bearing dims. But I think it was a uk site or these guys would know:

    http://http://www.allballsracing.com/
  16. bgoodsoil

    bgoodsoil Dare to be Stupid

    Joined:
    Jul 9, 2008
    Oddometer:
    4,687
    Location:
    Washington, DC, USA
    I tried that route already. I called All Balls. The OD of the BMW bearing is 52mm. The ID of the KTM bearing is 29mm. They don't have any bearings with that spec.
  17. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
    I'm confused. If you're using a DR race, what does it matter what the BMW bearing sizes are? The ktm bearing would be going into the DR race using the KTM stem
  18. Stagehand

    Stagehand Imperfectionist

    Joined:
    Oct 6, 2004
    Oddometer:
    32,532
    Location:
    Shawangunks
    mybrain jsut esploded
  19. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,875
    Location:
    Atlanta
  20. bgoodsoil

    bgoodsoil Dare to be Stupid

    Joined:
    Jul 9, 2008
    Oddometer:
    4,687
    Location:
    Washington, DC, USA
    ooooh you're talking about mixing a bearing with a different race? hmm....