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Carburettor problem

in 912 / 914 Technical Questions 8 years ago

  • Re: Carburettor problem

    by » 8 years ago

    Ball bearings?. there are ball bearings in these carbs?, on the throttle shaft or ?.

    Tom O.
      
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  • Re: Carburettor problem

    by » 8 years ago

    There are drillings that are made in the body to create the internal passages as they cannot be cast. The end of the drilling where it comes out of the body has to be blocked off and this has been done by forcing a small ball bearing into the end of the hole and it is then covered by epoxy resin.

    I hope that makes sense. If you take a look at one you can see the epoxy in a number of the holes.
      
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  • Re: Carburettor problem

    by » 8 years ago

    What you describe is called cross-drilling. It is a method to get two intersecting passages to connect usually at ninety degree angle. The access for the drill is then capped off - in this case buy pressing in a ball bearing.
      
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  • Re: Carburettor problem

    by » 8 years ago

    I have made some interesting discoveries this afternoon. I carried out some investigations on the bench this afternoon comparing my carbs with the ones that I had been loaned and this is what I found:

    1. The springs are different lengths (mine is shorter)
    2. The needle is set in a different position (mine is higher).
    3. The main jet mounting is different.
    4. The number on the body is different (mine: 64/32/417, yours: 64/32/422A).

    What do you make of this? Is any of it significant and relevant to my problem?

    Take a look at the photos. The file names indicate where the part shown is my original or from the loaned carb.

    Kevin
    OriginalshortestIMG_1708.JPG (You do not have access to download this file.)
    OriginalIMG_1710.JPG (You do not have access to download this file.)
    LoanedIMG_1711.JPG (You do not have access to download this file.)
    OriginalIMG_1712.JPG (You do not have access to download this file.)
    LoanedIMG_1717.JPG (You do not have access to download this file.)
      
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  • Re: Carburettor problem

    by » 8 years ago

    Kevin
    The springs should be the same length.

    You have carbs from a 912ULS & 912UL, they are different.
    The 912ULS is carb 422A & 912UL is 417A.
    The diffusers are different as shown in you pictures as well as a number of other jets.
    I would not recommend using carbs of 912UL on 912ULS or vice versa
      
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