Needle bearings comparison

Discussion in '2-Stroke Engines' started by 210061741, Nov 30, 2009.

  1. 210061741

    210061741 Guest

    Hopefully this will be useful info.
    There are 3 different bearings in the pictures.

    10x14x10 = Grubee 48cc wristpin bearing (THE BROKEN ONE)
    Notice the rings worn into the needles where they were riding in the cage.
    This bearing had 2000 MI on it.

    10x14x13 = PK80-J wristpin Bearing (The larger Silver One)
    Brand new, didn't look bad at all.
    I liked the fact that it is 3mm wider than the Grubee.
    I actually put this bearing in my Grubee.
    Only needed to file a little off of each boss inside the piston to fit it.
    Seems to be working good.

    10X14X13 = Sthil 028 chainsaw bearing (the large copper one)
    These are the high performance replacement.

    You can clearly see the part number.. any Sthil dealer can order them for you. mine cost about $10.oo each.
    Supposedly these are rated to 13000 RPM.
    The cage is much thicker and at the wristpin the RPM is actually low.
    So the cage skidding the rollers isn't a problem.
    It is the rocking back and fourth breaks the cages.
    Copper is soft and will flex alot more before it breaks.

    I'm putting one of these in the PK80-J so we will see how it holds up.
    The PK80-J has cageless / crowded needle bearing on the bottom end. (23 needles)
    The grubee has a 13 roller caged bearing.

    I like to run my motors at 6000 to 8000 RPM.
    The Grubee bottom end is not happy with me.:sweatdrop:
     

    Attached Files:


  2. DJEEPER

    DJEEPER Member

    do you know what the macro function is?
     
  3. 210061741

    210061741 Guest

    Not sure exactlly what youre reffering to.
    I know macro as far a software is like in MS Access or MS Excell.

    Or are you talking Macroscopic.
    Like in metalurgy.

    Other than that maybe you talkin about my camera.
    Some of the pictures get a little blurry.
    Tried everything.
    This camera must be chineese.

    You still can see what you need to.
     
  4. mountain80

    mountain80 Member

    The cage is not copper it is copper plated and yes they ARE rated for aproximately 13,000 rpm my father repairs small engines and that engines max rpm is in that area.
     
  5. 210061741

    210061741 Guest

    Thats cool.
    I believe i found out about the Sthil 028 bearing from your post.
    Decided to trust what you said and bought 2 of them.
    1 is going in my brand new PK80-J.

    As far as i knew most of these were copper with silver plating.
    Do you know what the base Metal is?
    How much have you tesed them?

    Thanks
    Rich
     
  6. 210061741

    210061741 Guest

    yes it is confirmed.
    --------------------------------------------------------------------------------

    Sthil 028 chainsaw.
    Shop Manual says 13,000 rpm. maximum with bar & chain tensioned.

    That is more than enough Rpm for me.
     
  7. velzie

    velzie Member

    I just returned from my local Sthil dealer and bought the part from the part number on the package. The parts guy said this part is not for a 028, but it didnt matter. This new bearing weighs 4.9g. Im too lazy to remove my original bearing from my 66cc grubee skyhawk to weigh it, but i will put it up here when i do.

    Previously to buying this upgraded top end needle bearing I was showed bearings of similar size but had cages that were made of a type of plastic. I think the material is poly amide 66 and has the designation TN which is at the end of the bearing identification. Theses bearings are not suggested by SKF for temperatures exceeding 120C(248F) using synthetc oil. HERE is SKF's wesite with cage material properties.


    20140129_132254.jpg
     
    Last edited: Jan 30, 2014
  8. Fabian

    Fabian Well-Known Member

    I have "never" had a small end connecting rod needle bearing fail, but i have had no end of problems with the caged big end connecting rod needle bearing, as described in the below link:

    http://motorizedbikeforum.the-talk.net/t298-connecting-rod-bearing-failure-analysis-chinese-bicycle-engine

    The newer engines all seem to have made the move to a crowded big end connecting rod needle bearing, which has drastically increased big end bearing life.
    My previous engine lasted 10,000 kilometers (6,000 miles) before the big end bearing was shot, though the engine was operating with a Jaguar CDI.
     
  9. velzie

    velzie Member

    Just for fun I weighed the stock top-end needle bearing from my Grubee Skyhawk 66cc (late 2013) motor as well as the equivalent STIHL bearing (pictured in my previous post). I did this on an analytical balance.

    Stock: 5.0153 g
    STIHL: 4.8970 g

    The difference is likely not going to be noticeable. I'd like to drill out my wrist pin or buy a titanium pin to reduce mass...
     
    Last edited: Feb 10, 2014
  10. jaguar

    jaguar Well-Known Member

  11. velzie

    velzie Member

    One of these things just isn't like the other...

    All I can tell you is they do not look the same. I believe mine are the same as the OP which is different from the one you linked to.
     
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