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Carby gasket Bendix carby

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  • 408
    408
    11 days ago
    Quoting Merv on 21 Nov 2025 07:34 AM

    I'm still not settled with this old girl yet, as just when I think I have got it right, it goes all crazy again, and I think it has something to do with how hot it gets. So, I have come to the conclusion that it has to be sucking air somewhere. I replaced the O rings in the manifold when I put the carby kit in the old Bendix, however it seemed such a flimsy setup it was hard to have confidence in the design. So this time I am making sure to eliminate the manifold as a problem. My local parts guy supplied me with two hi tech sealing rings (wish I'd asked what they were called) guaranteed to seal anything, and you can see in the pics that they are squarish with elongated ridges on the inner, outer and both side surfaces. Cost $14 each and not cheap, but worth every penny. A comparison of the profile compared to the O ring is in about the 3rd. pic. Very easy to fit, as I stretched them over the outer area of the manifold where the clamp rests, held the manifold in position and simply slid the seals into the channel between the manifold and the barrel. They are a tight fit, and being proud will still compress, filling the gap even more when the clamps are tightened. I now just have to get my square plus small spirit level to make sure I have the carby face exactly vertical before retightening. Love the sound of this old bike, but every time I start it my two dogs race into the house to hide, trembling, so reckoned I won't start it again until I can work out how to quieten it down a bit. But reckon when I get these clamps up tight tomorrow and the Mikuni back on, I won't be able to resist it. Will let you know how they go.

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    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.
  • Hilly
    Hilly
    11 days ago
    Quoting Merv on 21 Nov 2025 07:34 AM

    I'm still not settled with this old girl yet, as just when I think I have got it right, it goes all crazy again, and I think it has something to do with how hot it gets. So, I have come to the conclusion that it has to be sucking air somewhere. I replaced the O rings in the manifold when I put the carby kit in the old Bendix, however it seemed such a flimsy setup it was hard to have confidence in the design. So this time I am making sure to eliminate the manifold as a problem. My local parts guy supplied me with two hi tech sealing rings (wish I'd asked what they were called) guaranteed to seal anything, and you can see in the pics that they are squarish with elongated ridges on the inner, outer and both side surfaces. Cost $14 each and not cheap, but worth every penny. A comparison of the profile compared to the O ring is in about the 3rd. pic. Very easy to fit, as I stretched them over the outer area of the manifold where the clamp rests, held the manifold in position and simply slid the seals into the channel between the manifold and the barrel. They are a tight fit, and being proud will still compress, filling the gap even more when the clamps are tightened. I now just have to get my square plus small spirit level to make sure I have the carby face exactly vertical before retightening. Love the sound of this old bike, but every time I start it my two dogs race into the house to hide, trembling, so reckoned I won't start it again until I can work out how to quieten it down a bit. But reckon when I get these clamps up tight tomorrow and the Mikuni back on, I won't be able to resist it. Will let you know how they go.

    a1.jpg
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    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    It's a trike 😜
  • 408
    408
    11 days ago
    Quoting Merv on 21 Nov 2025 07:34 AM

    I'm still not settled with this old girl yet, as just when I think I have got it right, it goes all crazy again, and I think it has something to do with how hot it gets. So, I have come to the conclusion that it has to be sucking air somewhere. I replaced the O rings in the manifold when I put the carby kit in the old Bendix, however it seemed such a flimsy setup it was hard to have confidence in the design. So this time I am making sure to eliminate the manifold as a problem. My local parts guy supplied me with two hi tech sealing rings (wish I'd asked what they were called) guaranteed to seal anything, and you can see in the pics that they are squarish with elongated ridges on the inner, outer and both side surfaces. Cost $14 each and not cheap, but worth every penny. A comparison of the profile compared to the O ring is in about the 3rd. pic. Very easy to fit, as I stretched them over the outer area of the manifold where the clamp rests, held the manifold in position and simply slid the seals into the channel between the manifold and the barrel. They are a tight fit, and being proud will still compress, filling the gap even more when the clamps are tightened. I now just have to get my square plus small spirit level to make sure I have the carby face exactly vertical before retightening. Love the sound of this old bike, but every time I start it my two dogs race into the house to hide, trembling, so reckoned I won't start it again until I can work out how to quieten it down a bit. But reckon when I get these clamps up tight tomorrow and the Mikuni back on, I won't be able to resist it. Will let you know how they go.

    a1.jpg
    a2.jpg
    a3.jpg
    a4.jpg
    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    Quoting Hilly on 22 Nov 2025 12:28 AMedited: 22 Nov 2025 12:28 AM

    It's a trike 😜


    Ok , missed that.
    Will be close to vertical a lot.
  • Merv
    Merv
    11 days ago
    Quoting Merv on 21 Nov 2025 07:34 AM

    I'm still not settled with this old girl yet, as just when I think I have got it right, it goes all crazy again, and I think it has something to do with how hot it gets. So, I have come to the conclusion that it has to be sucking air somewhere. I replaced the O rings in the manifold when I put the carby kit in the old Bendix, however it seemed such a flimsy setup it was hard to have confidence in the design. So this time I am making sure to eliminate the manifold as a problem. My local parts guy supplied me with two hi tech sealing rings (wish I'd asked what they were called) guaranteed to seal anything, and you can see in the pics that they are squarish with elongated ridges on the inner, outer and both side surfaces. Cost $14 each and not cheap, but worth every penny. A comparison of the profile compared to the O ring is in about the 3rd. pic. Very easy to fit, as I stretched them over the outer area of the manifold where the clamp rests, held the manifold in position and simply slid the seals into the channel between the manifold and the barrel. They are a tight fit, and being proud will still compress, filling the gap even more when the clamps are tightened. I now just have to get my square plus small spirit level to make sure I have the carby face exactly vertical before retightening. Love the sound of this old bike, but every time I start it my two dogs race into the house to hide, trembling, so reckoned I won't start it again until I can work out how to quieten it down a bit. But reckon when I get these clamps up tight tomorrow and the Mikuni back on, I won't be able to resist it. Will let you know how they go.

    a1.jpg
    a2.jpg
    a3.jpg
    a4.jpg
    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    I need to have the manifold face vertical, otherwise the mating surfaces at the head will be eccentric and not seal properly. Bike is level almost always.
  • 408
    408
    11 days ago
    Quoting Merv on 21 Nov 2025 07:34 AM

    I'm still not settled with this old girl yet, as just when I think I have got it right, it goes all crazy again, and I think it has something to do with how hot it gets. So, I have come to the conclusion that it has to be sucking air somewhere. I replaced the O rings in the manifold when I put the carby kit in the old Bendix, however it seemed such a flimsy setup it was hard to have confidence in the design. So this time I am making sure to eliminate the manifold as a problem. My local parts guy supplied me with two hi tech sealing rings (wish I'd asked what they were called) guaranteed to seal anything, and you can see in the pics that they are squarish with elongated ridges on the inner, outer and both side surfaces. Cost $14 each and not cheap, but worth every penny. A comparison of the profile compared to the O ring is in about the 3rd. pic. Very easy to fit, as I stretched them over the outer area of the manifold where the clamp rests, held the manifold in position and simply slid the seals into the channel between the manifold and the barrel. They are a tight fit, and being proud will still compress, filling the gap even more when the clamps are tightened. I now just have to get my square plus small spirit level to make sure I have the carby face exactly vertical before retightening. Love the sound of this old bike, but every time I start it my two dogs race into the house to hide, trembling, so reckoned I won't start it again until I can work out how to quieten it down a bit. But reckon when I get these clamps up tight tomorrow and the Mikuni back on, I won't be able to resist it. Will let you know how they go.

    a1.jpg
    a2.jpg
    a3.jpg
    a4.jpg
    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    Quoting Merv on 22 Nov 2025 02:07 AM

    I need to have the manifold face vertical, otherwise the mating surfaces at the head will be eccentric and not seal properly. Bike is level almost always.


    Will say again, level, square and vertical are not important.
    Most important is fit of manifold to heads. get the best fit and tighten, check as you go.
  • Merv
    Merv
    11 days ago
    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    Quoting Merv on 22 Nov 2025 02:07 AM

    I need to have the manifold face vertical, otherwise the mating surfaces at the head will be eccentric and not seal properly. Bike is level almost always.

    Quoting 408 on 22 Nov 2025 02:31 AM


    Will say again, level, square and vertical are not important.
    Most important is fit of manifold to heads. get the best fit and tighten, check as you go.

    Talking about the same thing I think, just different pic in our minds. There are two clamps in place covering the manifold/head joints now and I can not see if correctly aligned, so would have thought that HD would have machined the manifold surface where the carby bolts to so it would be vertical when fitted to a level sitting bike. Other than that, at this stage of tightening the clamps, I do not know another way to ensure it is properly aligned? But eager to be educated.
  • 408
    408
    11 days ago
    Quoting 408 on 22 Nov 2025 12:26 AM


    I have seen similar seals in brake calipers to ensure a better seal on the piston.
    I would not be too fussed about checking vertical. The engine would also need to be dead vertical. 
    Better to ensure a good seal at the head.
    The bike will not often be operating at vertical.
    If you are concerned about the float level, Archimedes says the volume of fuel in the bowl would be the same.

    Quoting Merv on 22 Nov 2025 02:07 AM

    I need to have the manifold face vertical, otherwise the mating surfaces at the head will be eccentric and not seal properly. Bike is level almost always.

    Quoting 408 on 22 Nov 2025 02:31 AM


    Will say again, level, square and vertical are not important.
    Most important is fit of manifold to heads. get the best fit and tighten, check as you go.


    The bike may be level, that doesn't mean the engine is vertical.
    If the engine is vertical, that doesn't mean the best fit for the carby is vertical. It may well be, but not necessarily.
    Have you checked whether both cylinders are in the same vertical plane ?
    The carby to manifold is often straight forward. If there is an intake leak it is most likely where the manifold fits the heads.
    Ideally you will get a good concentric fit at each head surface. You should be able to feel it.
    You could make up a cardboard template to check for eccentricity of fit at each head prior to assembly if you have any doubts, but you still need the best fit at each head/manifold interface.
    You also need to ensure the carby support bracket does not pull it out of alignment.
    Best to do a loose fit and tighten carby support bracket first, then pinch the other bolts/screws tight.


  • Merv
    Merv
    11 days ago
    Quoting Merv on 22 Nov 2025 02:07 AM

    I need to have the manifold face vertical, otherwise the mating surfaces at the head will be eccentric and not seal properly. Bike is level almost always.

    Quoting 408 on 22 Nov 2025 02:31 AM


    Will say again, level, square and vertical are not important.
    Most important is fit of manifold to heads. get the best fit and tighten, check as you go.

    Quoting 408 on 22 Nov 2025 05:33 AM


    The bike may be level, that doesn't mean the engine is vertical.
    If the engine is vertical, that doesn't mean the best fit for the carby is vertical. It may well be, but not necessarily.
    Have you checked whether both cylinders are in the same vertical plane ?
    The carby to manifold is often straight forward. If there is an intake leak it is most likely where the manifold fits the heads.
    Ideally you will get a good concentric fit at each head surface. You should be able to feel it.
    You could make up a cardboard template to check for eccentricity of fit at each head prior to assembly if you have any doubts, but you still need the best fit at each head/manifold interface.
    You also need to ensure the carby support bracket does not pull it out of alignment.
    Best to do a loose fit and tighten carby support bracket first, then pinch the other bolts/screws tight.


    Sure wish I had your knowledge. But if this manifold ever leaks air at either joint, I'll walk to Bourke and back buck naked. And having a pegleg, that's saying something. But I have a rough idea of what you're talking about, and working it up and down about a quarter inch before tightening to make sure the seals were properly seated made it feel like it found it's own center. Carby is now refitted and looks ok, so I will sleep well tonight. Club ride tomorrow if not raining so Monday might be fire-up. In no hurry, cos I'm keeping it forever.
  • 408
    408
    11 days ago
    The manifold needs to be in its happy place with the seals at the intake opening in the heads.
    That is the most important thing.

  • Hilly
    Hilly
    6 days ago
    You been quiet Merv, how did you go with the manifold? Sorted?
  • Merv
    Merv
    6 days ago
    Quoting Hilly on 26 Nov 2025 11:11 PM

    You been quiet Merv, how did you go with the manifold? Sorted?

    Hi Hilly, been busy with life mate. Bad storms every night since, with some storm damage and lots of cleaning up during the day. Plus a bit of a rare heatwave going through and forecast 37c today. Had my scooter parked beside wife's nice Honda car under the carport, and would you believe the wind blew the bike over onto her car. Big dent. Steelbuilt shelves blew over onto car.
    But I am happy the manifold won't suck air due to those seals. They are the bees knees. Have the carby fitted, and just want to check the timing again with the test light, so will get motivated again when the storms ease and the temp. drops a bit.
  • Hilly
    Hilly
    5 days ago
    Bloody hell mate! Bike ok? 😜
  • Merv
    Merv
    4 days ago
    Quoting Hilly on 28 Nov 2025 04:54 AM

    Bloody hell mate! Bike ok? 😜

    Yes mate, the LS650 is out in the carport but was a bit heavy for the wind to move. Others all good in the back shed. Couldn't hurt the scooter if you tried.
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