Problems with Pike 454- Mtbr.com
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  1. #1
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    Problems with Pike 454

    I'm hoping someone out there with a Pike has some insight into a couple of problems I'm having with my new Pike 454. The first issue is that when I pump air into the negative chamber accessed by the bottom of the fork leg, it seems to release air as I unscrew the pump (and not just the air trapped in the screw mechanism). Over many attempts yesterday, I pumped 135lbs into the negative chamber and then unscrewed the pump - and air rushes out. I then immediately screwed it back on, and the pressure gauge registers ~95-100lbs. This doesn't happen when I pump air into the positive chamber. When I do this same exercise on the positive chamber, the pressure is still 135lbs when I re-check it.

    Problem number 2: My fork will not extend beyond 125mm, static/unweighted with the U-turn turned all the way up. This started yesterday (after owning it for 2 wks, 8 rides). It was like that for the whole ride, and is still like that this morning. I tried letting the air out of both chambers and refilling them to make sure they were relatively equal (subject, of course, to the limitation in problem # 1 above). Do you know what would cause this?

    Thanks for any help you might be able to offer.

  2. #2
    Bring Back Buck
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    Umm...

    Tim,
    I had the air issue with my negative chamber too, as did a friend of mine. Basically, as far as I can see, the negative chamber is a bit on the small side, there fore a small amount of of air escaping will have a big effect. We've both got around the proiblem by over compensating for the loss of air when pumping the fork up, filling the negative chamber first.

    No idea about your second issue - maybe you should dismantle it, clean and re-grease the seals, throw in some fresh oil and see what happens? The only other thing I can think of is that you may have too much air in the negative chamber?

    Hope that helps.

    Buck.

  3. #3
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    For problem #1 you need the acu-fill adapter made by Risse Racing... http://www.risseracing.com/product_accessories.shtml This thing works great for disengaging your pump without losing air.

    I have no idea about problem #2.

  4. #4
    Lay off the Levers
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    For problem #1, you may have a slightly sticky valve core. Dry putting a few drops of oil into the valve stem then either hold it down with a tool to let it drip in or screw the pump on. Work the valve a few times with a tool to hopefully spread the oil in the valve core shaft and seat. Don't use too much oil or you will reduce the chamber volume. But you can always drain the excess by holding the valve down and letting the oil drip out.
    Faster is better, even when it's not.

  5. #5
    Living the Dream
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    Dusty, which adapter do you order?

    The Acu-fill Adapter
    Price: $12.00

    The Acu-Fill Adapter fits onto the end of your suspension pump and prevents air loss when you disconnect the pump from your shock or fork.

    Part # Description MSRP
    50062 Acu-Fill Adapter $12.00
    21098 Acu-Fill RS Adapter $10.00

    Click here for directions in PDF format.


    I am interested in using it for my DHX and eventually a lyrik 2 Step (once the bugs are worked out) Does the RS in the Part 21098 Adapter stand for Rock Shox?
    "And I shout that your all fakes and you should have seen the look on your face"

  6. #6
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    I had a negative chamber that lost all air in it when unscrewing the pump. Replaced the valve core with one from an old tube....and it works just fine now. Simple fix and costs nothing to try.

  7. #7
    Lay off the Levers
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    Some pumps come with a two stage adaptor built on the end. The small screw releases the valve pin first then the large screw releases the seal on the valve stem. Performance has a pump called the Aftershock Hurricane (looks exactly like the one below)... I got one for about $15 but I don't see it on their site lately. Look but there are several incarnations of the same thing....


    Faster is better, even when it's not.

  8. #8
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    Thanks

    Thanks to everyone with the advice on the adaptors, 2 stage pumps, and valve core solutions.

    I figured out why the fork stuck at 125mm. I had overcompensated pumping up the negative spring...there was more pressure in the negative than in the positive. As soon as I let out some pressure from the bottom, the fork went right back up to 140mm.

  9. #9
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    Quote Originally Posted by Alpenglow
    The Acu-fill Adapter
    Price: $12.00

    The Acu-Fill Adapter fits onto the end of your suspension pump and prevents air loss when you disconnect the pump from your shock or fork.

    Part # Description MSRP
    50062 Acu-Fill Adapter $12.00
    21098 Acu-Fill RS Adapter $10.00

    Click here for directions in PDF format.


    I am interested in using it for my DHX and eventually a lyrik 2 Step (once the bugs are worked out) Does the RS in the Part 21098 Adapter stand for Rock Shox?
    Yes, RS stands for Rock Shox. I got the standard version since I use it for Fox products.

  10. #10
    Bodhisattva
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    Guys, no need for this type of stuff with a Fox or RockShox pump. They come with a pin inside the head that releases before any air escapes from the shock's schraeder.

    If you notice "air loss" when putting the pump on the shock it's because air is escaping into the pump which gives a falsely low read.

    Y'all are spinning your wheels for no reason.

  11. #11
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    Quote Originally Posted by The Squeaky Wheel
    Guys, no need for this type of stuff with a Fox or RockShox pump. They come with a pin inside the head that releases before any air escapes from the shock's schraeder.

    If you notice "air loss" when putting the pump on the shock it's because air is escaping into the pump which gives a falsely low read.

    Y'all are spinning your wheels for no reason.

    If so, how come I don't get this false read on the positive chamber? And what about the cloud of dust-infused air that bursts outward when I disengage the pump? (again, this doesn't happen on the positive chamber...I only get a poof of that little bit of pent up pressure in the pump itself)

  12. #12
    Bodhisattva
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    Quote Originally Posted by Tim C Boston
    If so, how come I don't get this false read on the positive chamber? And what about the cloud of dust-infused air that bursts outward when I disengage the pump? (again, this doesn't happen on the positive chamber...I only get a poof of that little bit of pent up pressure in the pump itself)
    can't answer that for ya. But I can tell you how the pump is designed.

  13. #13
    Lay off the Levers
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    The answer is A and B

    The valve pin is resessed such that it is released before the pump is fully disengaged.
    If the valve is sticky and slow to close it'll let air blow out anyway. The rushing air could help force it closed as opposed to the static chamber pressure while the pump is still attached but not engaging the pin.

    Either oil the valve or change it and let us know what happens.
    Faster is better, even when it's not.

  14. #14
    Natl. Champ DH Poser/Hack
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    .... he says again 5 hours later. ill bet this is exactly whats goin down. change the valve.
    No, I'm NOT back!

  15. #15
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    Another question

    So continuing this conversation..... when you fill you fork/shock do you fill it to the pressure you want and then remove the pump or do you fill over the pressure to compensate for the air released,

    I find when i pump to a desired psi (120) then reconnect the pump, the psi is now lower (115, 100) depending on the size of the chamber.

    To compensate I do this.

    Fill the chamber to above the desired psi (130 for 120). Disconnect and reconnect to check. If I'm just right I fill again to 130 psi to achive the 120psi from the list presure when releasing.

    I have been doing this for my revelation fork and dhx air on my 5 spot.

    Is this incorrect? Should I get the same pressure 120 if I fill up to 120 psi and reconnect (get 120psi again)?

    Please help.

  16. #16
    rr
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    Just fill it to the pressure you want, you shouldn't lose any air when removing it, when you reinstall the pump you lose some psi cause air fills the pump body.

  17. #17
    MK_
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    Quote Originally Posted by Tim C Boston
    If so, how come I don't get this false read on the positive chamber? And what about the cloud of dust-infused air that bursts outward when I disengage the pump? (again, this doesn't happen on the positive chamber...I only get a poof of that little bit of pent up pressure in the pump itself)
    When you screw your pump back to the negative chamber and air escapes to fill the hose, you get a lowered pressure reading. That much we know.

    The max extension of the fork is reached when the positive and negative chambers are at equilibrium. This is why you can over pump, so to speak, your negative chamber, to reduce the max travel of your fork.

    So when you reattach your pump to the positive chamber, the air which escaped is compensated for by the fork dropping a tad in the travel, which you can probably observe, or not, if it is really minute, and reaching a new equilibrium. The pressure does not change, because the pressure in the negative chamber controls the equilibrium pressure.

    _MK

    Before you diagnose yourself with depression or low self-esteem, first make sure that you are not just surrounded by a*holes

  18. #18
    rr
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    FWIW, a local RS engineer told us that when checking air pressure with the RS forks with pos/neg chambers you want to first let all the air out of the neg chamber(do this with the fork upside down so the oil is out of the way and doesn't spray as much) and then fill the pos chamber and lastly the neg chamber. By letting all the air out of the neg chamber this ensures the fork is fully extended before filling the pos chamber, of course your supposed to extend the fork to full travel on Uturn models too.

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