My small end bearing failed

Discussion in 'Motorized Bicycle General Discussion' started by biknut, Feb 19, 2012.

  1. Nashville Kat

    Nashville Kat Active Member

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    And can someone explain then how this differs from the BGF "Crank bearing"- beyoned the needle bearings-
    http://www.ebay.com/itm/bicycle-Mot...260?pt=LH_DefaultDomain_0&hash=item27abb6916c
    is this the same bearing? are they interchangeable?

    we want motor bike enthusiasts to get the correct info before spending money or tearing something apart to find parts don't work-

    how about an after repair performance report?
     
  2. biknut

    biknut Active Member

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    Those are crankshaft bearings. These are rod bearings for the connecting rod small end.
     
  3. mapbike

    mapbike Active Member

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    Anyone looking for inexpensive high quality small end wrist pin bearings can find them here,

    http://www.motionindustries.com/motion3/jsp/mii/productSearch.jsp

    this is where I get my bearing and high quality crank seals, many towns have a motion industries inc. in them, I have one close so I just have them order the bearings and they are here in 3-4 days normally.

    hope this help many, I highly suggest replacing the upper bearing asap in these china girl engines, in my experience they don't offer much warning before they go normally and when they do it usually mean, New Jug/Cylinder, New Piston, New Rings and a complete engine tear down.

    $3-$4 bearing is a small price to pay when you consider what it cost to rebuild the top end of the engine.....just my opinion here.

    Peace, map
     
  4. mapbike

    mapbike Active Member

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  5. biknut

    biknut Active Member

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    Do they have the one thin ones for the left side?
     
  6. Goat Herder

    Goat Herder Gutter Rider

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    Realized I posted these in your other thread but the way this one is titled it may help some one else? The stock wrist pin needle bearings on these motors are a nice joke that have been played on way too many people IMHO..

    http://www.twostroke.se/product.asp?product=12930
     
  7. The_Aleman

    The_Aleman New Member

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    I thought all the chinagirls were a joke. A mean one, at that. Maybe I'm biased, 3 of my 5 chinagirls blew up rotfl
     
  8. Toadmund

    Toadmund New Member

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    That's great but to ship 2 of them to New Brunswick, Canada would cost over $24.00 to ship.
    I'll have to look for another source.

    Maybe my local bearing supplier.
     
  9. biknut

    biknut Active Member

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    i would probably agree if it weren't for the Atomic BB being 2 1/2 years old and running great. It's twin brother, bought at the same time has less miles on it than mine, but it hasn't had any problems either. They're Flying Horse motors.

    I'm definitly thinking all the different motors I bought from the Rico group were pretty poor quality.
     
  10. Goat Herder

    Goat Herder Gutter Rider

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    I dunno? Sometimes this is more like taking my money to the gambling casino. I hate and don't go to those places. lol. Gambling never faired off for me assuming always got me in trouble too
     
  11. biknut

    biknut Active Member

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    I should report what happened to this motor that broke the needle bearing. It broke another one, and I found one more damaged before it failed.

    I've come to the conclusion that the rod small end is not properly machined, and that's what is causing the bearing failures.

    All 3 of the supposedly different motors I bought from the Rico group had crappy crankshafts.

    I've bought enough stock crankshafts now to have a basis for comparison. Now that I know what to look for I've seen a lot of variance in the quality of the machining of the rod small end. The problem is that the rod inside dia is also the bearing race for the needle rollers. If the rod isn't perfect, the needles will fail. that's what happened with this motor.

    IMO our biggest challenge is getting a china girl with a good crank.
     
  12. multipaul

    multipaul New Member

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    Hallo Biknut,

    you're absolutely right! That is what we should shout every day in the direction of China's manufacturers.

    In an upper answer you've said that INA comes from China. INA is a worldwide producing company with the main factory in Germany. They make needle bearings, special piston pin bearings and special conrod big end bearings.
    For my American friends I have been looking for INA's specification in English language about how to manufacture a connecting rod and the permitted tolerances. Here it is:

    http://www.schaeffler.com/remotemed.../schaeffler_2/tpi/downloads_8/tpi94_de_en.pdf

    Twostroke crankshafts which are manufactured according this specification, will carry you once around the world. At least half, as one would expect as a customer.

    Multipaul
     

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