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Another CRF1000L fork thread!! Reg vs Adv Sport forks.

Discussion in 'Japanese polycylindered adventure bikes' started by Motociclo, Oct 22, 2018.

  1. Motociclo

    Motociclo Long timer Supporter

    Joined:
    May 18, 2017
    Oddometer:
    1,082
    Location:
    Oz
    Anyone that has been reading my posts etc, realises I have a thing for forks and shocks.
    I have had the dreaded anodising wear on my 16 At twin.
    I have said before, and will say again, I think all 16 and 17 models will suffer the same fate.
    Alas, there are options.
    I had mine Kashima coated, thus far has held out well. But by the chance it fails, short of bolting on gold "O" forks. There is a cheaper option.

    (Edit, Kashima coating on my forks eventually wore through. Disappointed, but suggests to much flex in 16 to 18 outers.
    I feel that even the Kashima coated 18 outers will wear the same way. Hopefully not, would like to be proven wrong on this one. Time will tell. As of Dec. 2018, I have ordered outers and lowers adv sport fork bits. Hopefully they hold up ok. Will review them in time.)

    2018 at twin outer tubes. These have been updated with a Kashima coat, but the slider bush to outer tube clearance is still a bit loose.
    Part number for this part, 51410-MKK-D01
    This is a good enough option, but there is better. They are still the same tube, only coated. Still will flex a bit.

    Adv sport forks.
    This I feel is the better option.
    These forks as a complete set will bolt straight on. Same everything externally except the additional 20 plus mm travel. Will make front end sit up if you bolt straight on. Would need to sort rear also. Good option if you want the extra travel.
    The outer tube is Kashima coated and has a larger OD just above area where seal and guide Bush live.
    Reg af twin in this area is approx 51mm, adv sport is 55mm.

    Outer tube is same length as reg af twin outer.
    Lower leg is same length as reg twin outer.

    Even though they have longer travel, all internals are interchangeable. But some need other bits to fit in same cases. Some parts I don't recommend exchanging. Read on.

    The extra travel. This cames from a longer damper tube assembly.
    The lower leg and upper tube don't contribute to extra travel dimensionally. But, the lower leg has had the glide bush moved 20mm, (edit, measured at 29mm), higher to accommodate the extra travel. This gives good overlap of fork tubes to reduce flex.
    You could run the adv sport damper tube in reg af twin forks, but there isn't enough strength in the outer tube, combined with low placement of slider bush. Not enough overlap of fork tubes. A rider sag of say 70mm, would pretty much have the bush sit below triple clamp area. Which is lower than current set up. Current set up sits pretty much in lower clamp area. Not advisable at all.
    Reg af twin slider bush location is approx 35mm from top.
    Adv sport slider bush location is approx 15mm from top.


    Aside from this, parts are identical. Even running the adv sport lower in reg forks, gives an extra 29mm overlap where bush sits. This helps reduce flex.
    This is another option.
    Here is a pic to illustrate.
    I run about 65mm sag, so this pic relevant to my set up.
    Red dot, slider bush location if you used adv sport damper tube in reg af twin forks. Not recommended.
    Blue dot, current slider bush location, with my set up. Reg af twin forks.
    Green dot, this is the slider bush location using adv sport lowers with reg af twin damper rod with either stock upper tube or using adv sport lower/ upper tube combo.

    20181023_153058.jpg
    In pic below, red line is top of Bush on reg af twin lowers.
    Green line is approx were bush lives on adv sport lowers.

    20181023_182212.jpg

    Quick summary of parts that will fit but need to be together.
    Adv sport damper tube and fork cap assembly. Longer tube, equals longer rebound needle. Adv sport rebound needle won't fit reg af twin due to length. Don't recommend this option in reg af twin forks, as stated earlier.
    If you like the look of adv sport fork cap, buy it, rebound needle screws out and replace with reg af twin needle. Not really necessary.
    The adv sport fork springs are longer. If you ran them, it would be advisable to trim spacer.
    If bolting reg af twin damper assembly into Adv sport upper and lower, you use all you current internals. Straight swap.


    As for the rest, dimensionally, all other parts fit. Different part numbers on some bits, but they fit.
    Seals, bushes, spring spacer etc are all 100% interchangeable.
    Adv sport outers tubes are a straight swap into stock triple clamps. Zero mods.
    The lowers are also a straight swap.

    This is my recommendations. From don't do to best option with oem parts.

    Don't.
    I wouldn't recommend using adv sport damper rod assembly in reg af twin forks. Not enough strength to accommodate additional travel. As mentioned above.

    Better,
    Run adv sport upper with reg af twin lower leg,
    This option is more than adequate. Will certainly be a huge improvement over the regular Af Twin outers.

    Best oem parts option.
    Adv sport upper and lower legs, using reg af twin damper assembly.
    You get less flex with stronger upper tube, plus more overlap of the 2 tubes.
    Plus you get Kashima coated outers.

    Part numbers,
    Adv sport upper, 51410-MKK-D21
    Adv sport lower, 51425-MKK-D21 right side.
    , 51525-MKK-D21 left side.

    With this option, if you have had your current forks re valved, just bolt together with your springs also, and away you go again. Less flex, better wearing coating. Simply, what Honda/Showa should have done in the first place.


    The one thing I am not sure of is the slider bush to outer tube clearance on adv sport tubes.
    Leaky seals on reg af twin forks is in part from to much slop in fork legs. The seal doesn't like it.
    I run a shim, (0.05mm, gives total of 0.10mm when wrapped around), behind slider bush on mine to reduce slop. Forks feel better with it, and no leaks since.

    (Edit, I have measured the ID of outer tube and the OD of the lower leg where bush seats on adv sport fork bits. The adv sport outer tube has same ID as reg twin tube, 47.06mm, but the OD on adv sport lower where bush sits, has slightly bigger OD, 43.96mm vs 43.86mm. In the order of 0.10mm. This is the same amount as what I shimmed my reg af twin bush to reduce slop. I didn't need to run shim behind bush on lower on new adv sport lower.)

    I think I have covered it all pretty much. If not I will add what's necessary.
    Hope this is of some value.

    Edit, Just to add a little extra, @Greg the pole has put together some great articles and vids, with heaps of pics of his fork rebuild etc. The big plus is he has given a list of alternate seals that can be used. Thanks Greg.

    https://thetenerist.wordpress.com

    Edit, edit
    I have received parts, upper and lower legs.
    Have measured bits up and are posted further on.
    #1
  2. xaviKR

    xaviKR Adventurer

    Joined:
    Jun 12, 2008
    Oddometer:
    26
    Location:
    La Conca de Barbera
    Great post!

    OUTER TUBE -> 343,89 x 2 = 687,78 €
    LOWER TUBE R -> 155,79 €
    LOWER TUBE L -> 159,3 €

    1002,87 € in parts...
    :becca
    #2
    Motociclo likes this.
  3. Motociclo

    Motociclo Long timer Supporter

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    Cheers.
    Still not a cheap option.
    Another option no less.
    #3
  4. Amphib

    Amphib A mind is like a parachute....

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    Thanks so much for sharing this motociclo. I've only had my 2017 a short while now bought new. It's definitely sounding like fork failure is a matter of not if, but when. Wonder if Honda will get around to a recall or warranty covered fix..... But thank you for looking out for us and I'll be revisiting this post once mine are ready.
    #4
    Motociclo and gve.mcmlxxiv like this.
  5. Greg the pole

    Greg the pole There are no stupid questions, only stupid people

    Joined:
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    Great post Motociclo , thanks for laying it out. Read in full.
    2016/2017 dust seal is still weak. Double up the springs.
    I have not had a look at the redesigned 2018 dust seal.
    Oh ya, is it guide or glide bush:y0!
    #5
    Motociclo likes this.
  6. Greg the pole

    Greg the pole There are no stupid questions, only stupid people

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    or double your pleasure with Ooooooooooooohlins... 2500 euro +/-200 euro.
    Straight bolt in. Use for life of bike, and sell on for half of what you paid for it.
    #6
    Iowa_ADV, xaviKR and twinrider like this.
  7. Motociclo

    Motociclo Long timer Supporter

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    Cheers.
    Guide or glide??
    Not sure. I call bush on chrome leg glide and bush on outer tube guide.
    #7
    Junglejeff1 likes this.
  8. yokesman

    yokesman Long timer

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    Or see if your friendly dealer will swap the ATAS upper for the AT, while getting warranty work. along with the other details n seal changes previously recommended due to more surfaces. I think I will wait until the leak shows up n try this method , the worse they can say is no, then follow Motos, G n Jeffs plans at home.thanks for the info, it is getting parred down to a workg solution without the Oh- My $.
    #8
  9. Greg the pole

    Greg the pole There are no stupid questions, only stupid people

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    if your dealer ok's the warranty work, they actually don't care which part they order for you.
    I gave the part numbers to mine, but totally forgot about the ATAS option. I'm getting the 2018 regular outers.
    #9
  10. madafakinges

    madafakinges SUPERENDURO

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    IMG_20181019_202957_HDR.jpg IMG_20181019_204733_HDR.jpg
    I use complet ATAS fork and i love it.​
    #10
  11. enigmakiwi

    enigmakiwi Adventurer

    Joined:
    Apr 14, 2018
    Oddometer:
    35
    Location:
    New Zealand
    Ordered two ATAS uppers today US$622.52 including $125.## shipping from the USA. Delivery 1st week in November, summer is turning up for those of us that walk and ride upsidedown on this planet.
    #11
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  12. motocopter

    motocopter Long timer

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    Have you ever unscrewed the springs and clipped off a coil or two; then, reconnect the ends? One end is tapered and acts like a screw. We used to do this on some Husky seals back in the early 80's in Phoenix.

    #12
  13. Greg the pole

    Greg the pole There are no stupid questions, only stupid people

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    sorry you asking me @motocopter ?
    If you are, I would never dare to cut springs. Spacers, all day, springs, nope.
    #13
  14. motocopter

    motocopter Long timer

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    I am as it seems you've done quite a bit with forks and such. Also, I was referring to the springs in fork seals.

    #14
  15. Greg the pole

    Greg the pole There are no stupid questions, only stupid people

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    right!
    for the seals, I'm only stealing the bigger spring from the OEM oil seal, and doubling up on the dust seal.
    for the oil seal, I'll put in the kawasaki seals. They are a better design. I'll go over it on the video, when I get around to it...weather is excellent here still, so getting the riding in when I can.
    [​IMG]
    But for the fork springs, I simply went with rece tech springs, and called it done. They are linear, so no screwing around.
    #15
    motocopter likes this.
  16. enigmakiwi

    enigmakiwi Adventurer

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    Apr 14, 2018
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    35
    Location:
    New Zealand
    Got email today from US supplier (Babbitts Online), ATAS upper tubes on back order, no known availability at present.
    #16
  17. ski-line900

    ski-line900 Been here awhile Supporter

    Joined:
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    Location:
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    That's whom I ordered mine from. Were pretty quick to get them in. There are a few discount codes available for 10-15% off. I think it's ok to post them?
    #17
  18. enigmakiwi

    enigmakiwi Adventurer

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    Oddometer:
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    Yes, I got 15% discount while the items were in the cart. They will turn up someday. I dont have the stiction problem at the moment.
    #18
  19. madafakinges

    madafakinges SUPERENDURO

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    I did my fork servis after 10tkm no signs of wear.
    DSC03242.JPG
    #19
  20. Junglejeff1

    Junglejeff1 Long timer

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    Doesn't the adventure have like a inch longer extention that puts the 20mm higher bush in the same position as the 1000 l model?
    #20