Happt Time factory assembly - No wonder these engines keep failing

Discussion in '2-Stroke Engines' started by Fabian, Jan 31, 2010.

  1. Fabian

    Fabian Well-Known Member

    Holy heck - now i understand why these 2-stroke chinese engines keep failing.

    Bashing things into place with a hammer isn't exactly the correct assembly procedure.
    I made up a jig that screws into the 6mm crankshaft thread that allows the helical crankshaft output gear to be evenly pressed into place.
    I think that's why a good portion of these engines make so much gear noise - a slight amount of lateral movement is going to cause incorrect gear mesh.

    Last edited: Jan 31, 2010

  2. give me vtec

    give me vtec Active Member

    what did you expect... Ferrari precision??? That video is pretty much what I had in my head....

    Could be why grubee's tend to last a little longer... he personally visits the factory and approves the production process and quality controls of all the manufacturers that put out his engines.
  3. arceeguy

    arceeguy Active Member

    *Yawn* This video has been around for a while. With various importers trying to discredit other importers on "crude" manufacturing techniques.

    What I see is a person driving in a crank seal, with a seal driver and a hammer. I don't see anything unusual about that.
  4. Fabian

    Fabian Well-Known Member

    Ferrari precision is not to be expected but bashing in a crankshaft seal with the face of a hammer is totally unacceptable.

    How hard would it be to weld a bottle jack upside down with a limit stop and a correctly sized driver to press the seal into place.

    It's well within the bounds of third world technology.

    Last edited: Jan 31, 2010
  5. arceeguy

    arceeguy Active Member

    I see you corrected yourself on the part being installed. It is clearly a seal and not a gear, like you previously posted.

    It is being driven in with a production tool.

    Have you ever replaced a seal on an engine before? If you have, you'd know that they are driven in with a hammer.
  6. Esteban

    Esteban Active Member

    You DO get what you pay for with these kits. You can't expect much with a $99 kit on a $69 bicycle.
  7. Fabian

    Fabian Well-Known Member

    I've rebuilt the engine currently in my bike making a few modifications along the way.

    To press the crank seals into place i used a suitably sized socket and a large G-clamp to press the seal into place.
    No bashing the **** out of it with a hammer - i'll leave that for the Chinese factory.
  8. arceeguy

    arceeguy Active Member

    Right - tell the guy replacing the rear crank seal on your Holden to get a "large G-clamp" and press that seal in place.......
  9. Dilly Bar Rob

    Dilly Bar Rob Member

    +1, we bang 'em in there like that all the time at the shop :devilish: If at all possible we'll try to put a big socket or something on the seal (old seal can also be used). If space is at a premium, we'll just whack it in there with a good ol' hammer :jester:
  10. GearNut

    GearNut Active Member

    I have used sockets, sections of metal pipe, PVC sprinkler pipe, wooden blocks, ect. to drive in seals. Just lube 'em up, inside and out, then drive them in square and true.
    I have never had a quality seal fail on me yet *knock on wood*. I have had cheap seals that were too big for the counterbore fail though.
    Yes, I also have screw jacks, pilot sleeves ,and proper seal drivers that match the screw jacks. It all really depends on the application.
    Get 'er done!
  11. Stan4d

    Stan4d New Member

    I work on industrial equipment for a living. I have seen alot. I have seen seals "hammered" in place....I have seen them pressed in place. Failure rate was about the same. I was impressed that they gave him a real hammer, and did not make him use a stilson wrench left over from the previous production run.
  12. Mountainman

    Mountainman Active Member

    Get 'er done

    that's the main THING
    and that hammer is one of the best tools ever invented

    ride that THING
  13. Fabian

    Fabian Well-Known Member

    It's refreshing to see that someone uses the correct methods of installation.

    GearNut in quote: Yes, I also have screw jacks, pilot sleeves ,and proper seal drivers that match the screw jacks. It all really depends on the application.

    There's only one thing missing from your methods and it's vital: a perfectly clean and expertly pressed white lab coat.
    I wouldn't even think of rebuilding my bicycle engine or anyone else's without this critical item.
    Besides, i can charge twice the labour rate with a white lab coat, and a few dial indicators strategically placed around the workshop.

    Professionalism doesn't come at Walmart prices!
  14. arceeguy

    arceeguy Active Member

    And OCD takes years to develop!
  15. GearNut

    GearNut Active Member

    If I wore one of those lab coats while working on Harleys (my profession) I would probably loose business! :shock: LOL!
  16. stealthc9

    stealthc9 Member

    theres nothing wrong with what he's doing? thats how you replace the crank seal or initially place the crank seal in....its honestly not worth it to use a hydrolic press when you can place it in with 3-4 taps of the hammer....that's not bashing it into place lol.
  17. stealthc9

    stealthc9 Member

    Last edited: Feb 2, 2010
  18. swifty

    swifty New Member

    interesting video stealth....but i missed the part where they bashed the seals in with a hammer. lol.
  19. stealthc9

    stealthc9 Member

    umm if you call that bashing then i'd hate to see anything you put together. he was tapping the seal in with the seal driver (you'll notice him put the driver down towards the end)
  20. give me vtec

    give me vtec Active Member