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  1. #1
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    Small Block 8 with Stans Arch 29 / Won't Stay Inflated?!

    New 29er Stans Arch, factory yellow tape mounted with brand-new Kenda Small Block 8 2.1 won't hold air for 24hrs. Start out at 42# and end up with 10#, maybe in 8-10 hrs later.

    They inflated nicely and did the soapy water / shakey thing many times. I've hung them, layed them on bucket horizontal too.

    I've seen some posts saying that Kendas and the SB8 were slow to seal.

    Any thoughts or observations?
    Tallboy
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  2. #2
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    Kenda single ply tires have very porous sidewalls. You need to start with some extra sealant, get them inflated, do a short ride around the street, and repeat this the next day. After a few days they should seal well, but still not as good as other tires.
    Scott @ GO-RIDE.com
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  3. #3
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    i mounted mine ~2 weeks ago, i ride every other day ~7mi and only finally they started holding their pressure. when i first inflated them i had like pinhole leaks everywhere, the stan's filled the holes quickly, would leave white spots anywhere the hole was. i had to do the shake thing and reinflate before every ride. now they seem good though.

    this is for both the SB8 and Nevegal installed at the same time.

  4. #4
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    For my 26" tires, I generally put 3 scoops in (2.4 Mt. Kings) and air up to 60 psi. overnight. The higher pressure pushes the Stans into the small holes better IMHO. Usually that is all it takes. Sure, 3 scoops sounds like a lot, but I never worry about a thing afterwards...

  5. #5
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    Great recomendations, sounds like I just need to relax, add more sealant and wait it out.

    Any risk of riding on them just over 1+ hr rides? The bead has seated well so I can't imagine a burp, just maybe adding some air mid-ride if at all...
    Tallboy
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  6. #6
    29 some of the time...
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    Quote Originally Posted by Jeepnut22
    For my 26" tires, I generally put 3 scoops in (2.4 Mt. Kings) and air up to 60 psi. overnight. The higher pressure pushes the Stans into the small holes better IMHO.
    That is fine and dandy if you are using UST on UST, but the OP is using Stan's rims which could lose the tire or damage the rim at over 40psi. So in this case I would say it is a bad option.
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

  7. #7
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    Update

    Well, this isn't getting much better and now seem to be loosing MORE air overnight. Most pressure is gone within ~8 hrs.

    Noticed one of the valve stems was loose and slightly leaky / weeping. New to the tubeless thing, I didn't really check the stems to see they were tight (seemed snug at inception). Subsequently tightened by hand then maybe a half rotation with help from a wrench. Not very tight but definitely snug. Lost a ton of air after this. Could I have damaged the inner-seal on the stem ?

    Also noticed that I could see sealant had sealed between the bead and rim. Dry in most places but actively leaking in some spots. It seems like I'm dealing more with getting the bead and stem to stop leaking vs. the sidewall porosity that others have commented on.

    I added 1oz of additional sealant to the F rim last night via the injector and will do the same to R today. Is 1oz enough to 'top off' the tires? (I believe a scoop is 2oz?) I'm resting the rims on 5gal buckets to keep them horizontal.

    I will have to say, in 23 yrs of mountain biking, I've NEVER spent this much time goofing with tubes. Do I sound frustrated yet?
    Tallboy
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  8. #8
    addicted to chunk
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    Well since it's not a true UST tire, you may experience issues.

    I would NOT pump it up to 60 PSI like mentioned above....not smart with a non-UST tire. You may blow the tire off the rim, or damage the tire or rim.

    I have had minor issues with getting a non-UST Kenda to seal up, 3 scoops of Stan's & a few rides generally took care of the problem. The "shaking" & turning by hand doesn't seem to do the trick.
    Riding.....

  9. #9
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    Success !!!

    After injecting 1oz extra in each tire (2 scoops at new install) and a nice 10mi ride, they are sealing nicely. I haven't checked pressure with a gauge in 3 days but seem really good to the touch.

    Thanks for the help !!
    Tallboy
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  10. #10
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    Glad it worked out for you. My 29er came with SB8's and I was thinking of going ghetto tubeless with them. Extra sealant and a ride seams to be the final steps to success with the SB8's.

  11. #11
    g3h6o3
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    For my Nevegal that wasn't holding air, the trick was to ride it. Since it held air for a couple of hours, I inflated it and rode. After the 1st ride they kept air over night but down to 10psi. I repeated, after the second ride, still holding air, up to 20 psi. Repeated a third time and there you go, it stopped losing air!

    P.S. It was of a Flow rim FWIW
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