I've fitted a new rear tyre - dunlop d908 not listed on the dunlop sites

Discussion in 'Dakar champion (950/990)' started by Mouse, Dec 7, 2005.

  1. wsmc99

    wsmc99 Been here awhile

    Joined:
    Jan 9, 2004
    Oddometer:
    564
    Location:
    SD, CA.
    Yes, because the tire diameter numbers are not that far off between all the combos. I think anyone running stock springs in front and too much preload in the rear will encounter issues with stability.

    I think there is some inherant design issue with the 908 front that causes some issues as well.

    I'm about to run an MT21 front and a 908 rear. My front springs are .50 straight rate. I've run scorpions f & R, scorpion r with TKC rear and TKC's f & r and have had no issues. The Scorpions like rear preload. The TKC's wobble the chassis very slightly at full on knee dragging road race antics.

    I imagine there will be a slight reduction in rear preload necessary to make the 908 rear work just fine.

    The MT21 & 908 have a 708mm diameter, the Scorpion is 704mm, the Karoo & TKC's are 695mm. The 606 front is slightly smaller than the MT21 perhaps 704mm?
  2. Crashed Bad

    Crashed Bad Big man, little bike

    Joined:
    Feb 5, 2006
    Oddometer:
    2,355
    Location:
    Set the controls for the heart of the sun
    I am running 908 rear and a 606 front for about 4k (1st rear went at 2300). I mounted these straight away since they came as spares when I bought my bike used. I was completely terrified when I first took the bike over 80 and it started to oscillate, alot. A friend has a SER and experienced simlar trouble when he switched to the 908 rear. He runs an emig stabilizer on his bike. I love the 908 rear and find it very predictable; it slides on and off road when you romp the throttle, but without catching abruptly. It's also very disarming to people following you when you leave black streaks exiting corners on the pavement. I found the wobble to be much worse when the TT cases are on and it is loaded with gear. I've never experienced the weave while cornering, only when accelerating in a straight line past 80 mph.
  3. FastHotWheels

    FastHotWheels Chris Dempsey

    Joined:
    Feb 5, 2006
    Oddometer:
    61
    Location:
    Livermore CA
    That’s exactly the experience I have had, with the panniers on and loaded I took a 1000mile trip to the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:eek:ffice:smarttags" /><st1:country-region w:st="on"><st1:place w:st="on">US</st1:place></st1:country-region> moto GP, it was a down right terrifying ride. I installed the Scotts damper today and I’m waiting for my wife to get home and watch the kids so I can go out and give it a test ride, (hope it helps!):lol3
  4. FastHotWheels

    FastHotWheels Chris Dempsey

    Joined:
    Feb 5, 2006
    Oddometer:
    61
    Location:
    Livermore CA
    Thanks for all the help, I got the Scotts Damper installed and took it out for a “road” test this morning, now I can dial the wobble in and out of the equation. At 90mph I can now even try to start the wobble by shaking the bars and the Damper just stops it. All the confidence is back, I feel like I just got my bike back! That’s all for now I need to get back out on the bike!
    :clap
  5. wsmc99

    wsmc99 Been here awhile

    Joined:
    Jan 9, 2004
    Oddometer:
    564
    Location:
    SD, CA.

    Was that a 908 front and rear or just rear?
    If you had something different in front, what was it?
  6. jaydee1445

    jaydee1445 Footpeg Crash Tester

    Joined:
    Jul 20, 2006
    Oddometer:
    4,758
    Location:
    high sided into the orange grove
    908rr front and rear.:evil
  7. wsmc99

    wsmc99 Been here awhile

    Joined:
    Jan 9, 2004
    Oddometer:
    564
    Location:
    SD, CA.
    So I ran a freinds 950 along with mine side by each to test a theory.

    His bike had a new 908rr rear and MT21 front.

    Mine had a new 908rr and worn TKC front.

    Both running 32 psi front and rear.

    My theory was that the difference between front and rear dia/rad was the key. I know the stock figures for all the tires and I know that the Scorpions being sooo stable have a difference of +15mm in front. So my guestimate figured that the ideal ratio front to rear would be about +10-12mm.

    I tested my freinds bike at +18mm & +12mm first. There was a mph where it would shake a bit and then settle. Neither configuration was what I'd call flickable. So we added some more rear preload/ride height and tried +8mm which was really nice and flickable while still being stable pretty much no shake at all.

    We then tried it at +6mm and found it to be flickable but prone to bar shake more so than any other setting.

    I then moved to my bike and set it to +8mm to see if this was the magic number. Indeed it was great!

    So it looks as though the "sweet" range is +8mm -10mm in front.

    To do this I took the known delta of the tires (+8mm in the MT21/908rr case) and set the dynamic sag figures to be +0mm. +8mm (from tire) + +0mm (from sag/ride height) = +8mm total...Voila!

    In the case of my bike with the worn TKC front and new 908 rear the tire delta was -4mm front. I set my sag delta to +12mm front. -4mm + 12mm = +8mm and again, Voila! Great handling bike.

    I do think the inherent construction difference in the MT21 vs. TKC makes it a little busy at the front, but not dangerous in any way. Just a different feel.
  8. dagwood

    dagwood Banned

    Joined:
    Aug 25, 2003
    Oddometer:
    35,395
    Location:
    Vancouver, Not! BC...
    bump :evil
    anyway. what about the 990 with the super wide rear rim?

    anyone try the teraflex? it comes up bigger than the 908rr and quite abit less money.

    :lurk.

    I need to get a set soon so...what say the 990 owners. as in yesterday...
    the mt 21 front is a given but I'm ready to try the teraflex VS 908rr so.
  9. dagwood

    dagwood Banned

    Joined:
    Aug 25, 2003
    Oddometer:
    35,395
    Location:
    Vancouver, Not! BC...
    :ddog slackers
  10. scalci

    scalci Been here awhile

    Joined:
    May 14, 2008
    Oddometer:
    128
    Location:
    Hartbeespoortdam, North West, South Africa
    I went from the TCK 80 rear to the 908 rear, and must agree the first couple of km&#8217;s the rear of the bike was all over. But now with some km&#8217;s on it, the tyre hold well on tar and dirt. The only downside is the price of this in South Africa. If I convert this to US$ it is $333... :(<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
  11. edgy

    edgy Been here awhile

    Joined:
    Jun 11, 2007
    Oddometer:
    525
    Location:
    Gtown,SA
    You getting ripped,we paying about R1800!
  12. KTM BIGGER

    KTM BIGGER n00b

    Joined:
    Aug 25, 2006
    Oddometer:
    0
    Location:
    Tip of South Arfica
    Where is this from Edgy and what front are you using on the SE?
  13. Bonsai Elephant

    Bonsai Elephant Banned

    Joined:
    Jun 12, 2007
    Oddometer:
    18,756
    Location:
    The Hills
    Okay, time for me to stir up the pot...

    I need tyres for my 08 990ADV, but in Israel tyres are unbelievably expensive, really, think expensive then double it, then double it again, we are talking outrageous prices.

    I want something more dirt oriented than Scorpions, but as I use the bike everyday to get to work and back (only 30km round trip) they need to hold up to road use too, and with the prices they charge here I really need something with a little longevity.

    Recommendations please?

    Thanks!

    :thumb
  14. codys

    codys Lost in the Vizcaino

    Joined:
    Aug 1, 2006
    Oddometer:
    1,290
    Location:
    Salida,CO,USA
    I'd say Mefo Super Explorer if you can get it. Heidenau (sp) makes a similar tire too. Longevity, good on the paved, plus an upgrade in the off road area compared to a scorpion.

    908rr dunlops last pretty good too but the center knob will be mostly gone at 2k miles. I've pushed them 5.5k mile commuting with pretty much no knob left at the end.
  15. Bonsai Elephant

    Bonsai Elephant Banned

    Joined:
    Jun 12, 2007
    Oddometer:
    18,756
    Location:
    The Hills
    Very interesting, thanks.

    Do you recommend the matching front?
  16. codys

    codys Lost in the Vizcaino

    Joined:
    Aug 1, 2006
    Oddometer:
    1,290
    Location:
    Salida,CO,USA
    I put a conti tkc 80 on front because it grips well everywhere and have had them last 7k miles. Cupped to hell in the end though. Not good in the rocks (square edge rocks especially) though. SOft side wall=rim damage. I'm not in the rocks when in tour mode so tkc front and mefo/scorp rear works great.

    I match a pirelli mt-21 with the 908rr local COlorado riding. The stiff side walls of this combo makes rock damage to the rim much less likely. Decent on the road and damn solid off.

    Good luck.
  17. jsrider

    jsrider Long timer

    Joined:
    Jun 30, 2004
    Oddometer:
    3,495
    The Karoo T is another good option for a street-worthy tire that's better than the Scorp in the dirt but lasts a reasonable amount of time.