HD Forums Australia
Home
Online: Hilly
Topics

Carby gasket Bendix carby

1/2
  • Merv
    Merv
    9 days ago
    New member, so be kind. My Bendix off my 73 Ironhead, the original gasket to the manifold has two elengated holes near the stud holes. These match two holes on the carby face, however my intake manifold has no corresponding hole to match those in the carby and gasket. My replacement gasket does not have the elongated holes, so they are sealed when carby is attached to manifold. Is this a problem? As the holes in the carby seem to go to vents within the carby throat. Pics attached if I can work out how. Cheers, Merv.
    Carb gasket.jpg
    Carb gasket2.jpg
  • Hilly
    Hilly
    9 days ago
    Hey Merv, can't say as to the why of it but a bit of careful Stanley Knife work could replicate the slots if that helps, had quick google and the slots seem to be prevalent in most kits, maybe a different year had ports in the manifold, I don't know though.
    Screenshot_20250922-204352.png
  • speedzter
    speedzter
    8 days ago
    No matching holes in the manifold = don't stress and run the gasket as is if it has been working .

    If it's a new setup then maybe more research.
  • obisteve
    obisteve
    7 days ago
    Quoting Merv on 22 Sep 2025 08:02 AM

    New member, so be kind. My Bendix off my 73 Ironhead, the original gasket to the manifold has two elengated holes near the stud holes. These match two holes on the carby face, however my intake manifold has no corresponding hole to match those in the carby and gasket. My replacement gasket does not have the elongated holes, so they are sealed when carby is attached to manifold. Is this a problem? As the holes in the carby seem to go to vents within the carby throat. Pics attached if I can work out how. Cheers, Merv.

    Carb gasket.jpg
    Carb gasket2.jpg
    The elongated slots in the gasket will be so it matches up with the holes in carb and manifold no matter which  way round its assembled. If there no holes in your manifold, and it was a runner, as Speedzter says don't worry about no holes in the replacement gasket, that's not going to change anything.
  • Merv
    Merv
    7 days ago
    Quoting Merv on 22 Sep 2025 08:02 AM

    New member, so be kind. My Bendix off my 73 Ironhead, the original gasket to the manifold has two elengated holes near the stud holes. These match two holes on the carby face, however my intake manifold has no corresponding hole to match those in the carby and gasket. My replacement gasket does not have the elongated holes, so they are sealed when carby is attached to manifold. Is this a problem? As the holes in the carby seem to go to vents within the carby throat. Pics attached if I can work out how. Cheers, Merv.

    Carb gasket.jpg
    Carb gasket2.jpg
    Quoting obisteve on 24 Sep 2025 01:02 AM

    The elongated slots in the gasket will be so it matches up with the holes in carb and manifold no matter which  way round its assembled. If there no holes in your manifold, and it was a runner, as Speedzter says don't worry about no holes in the replacement gasket, that's not going to change anything.

    Just appears that there is a feature on the carby that is not being used, and if used may improve the running. Thought perhaps my manifold was wrong. But thanks for the replies. I'll leave it as is. Cheers.

  • obisteve
    obisteve
    7 days ago
    And when it's back together, could you please post a pic of it?
    Some of us on here like Sportsters a lot.
    My records indicate that 1973 was the first year for the Bendix, but the Sportsterpedia should be able to confirm or deny that.
  • Merv
    Merv
    6 days ago
    Quoting obisteve on 24 Sep 2025 09:56 AM

    And when it's back together, could you please post a pic of it?

    Some of us on here like Sportsters a lot.
    My records indicate that 1973 was the first year for the Bendix, but the Sportsterpedia should be able to confirm or deny that.

    I'm an 81yo amputee. This should keep me in the saddle for the next 10 years or so.
    20250908_125038_resized.jpg
    20250908_125100_resized.jpg
    20250908_125112_resized.jpg
  • Stuart
    Stuart
    6 days ago
    Quoting obisteve on 24 Sep 2025 09:56 AM

    And when it's back together, could you please post a pic of it?

    Some of us on here like Sportsters a lot.
    My records indicate that 1973 was the first year for the Bendix, but the Sportsterpedia should be able to confirm or deny that.

    Quoting Merv on 24 Sep 2025 10:28 PM

    I'm an 81yo amputee. This should keep me in the saddle for the next 10 years or so.

    20250908_125038_resized.jpg
    20250908_125100_resized.jpg
    20250908_125112_resized.jpg
    Very cool bike, Merv.
  • Hilly
    Hilly
    6 days ago
    That's a cracker bike Merv, good stuff mate 👍
  • Merv
    Merv
    2 days ago
    Ok, still having carby problems. Book and forum says use 3/16 drill between carby body and float to set the height, however my float has had holes soldered and is a little heavier than normal, and setting this way brings the fuel level in the bowl to the top of the carby. Result is it idles and responds to throttle great when stopped, but immediately breaks down under acceleration. Read from an unreliable source that fuel level should be 9/16" below bottom of carby, which I have set using glass jar method as shown in pic below. However float is now so low the bowl closes it off when attached to the carby. Anyone know what distance below the carby bottom the fuel level should be? 
    20250927_151523_resized.jpg
    20250927_151528_resized.jpg
  • Hilly
    Hilly
    2 days ago
    Are you using the spring Merv?
  • Merv
    Merv
    2 days ago
    Quoting Hilly on 29 Sep 2025 06:41 AM

    Are you using the spring Merv?

    Yes mate. Problem isn't sticking needle, just bad adjustment. Trying to determine the fuel height in the bowl to set it rather than 3/16" drill method due to changed weight of float due to soldering holes. New floats are some $300 of our dollars landed, and would rather walk than pay that for a bit of brass. Mikuni carbs brand new are cheaper. But want to stay original. 

  • Hilly
    Hilly
    2 days ago
    I understand, the 3/16 method is the only one I know, I'm thinking with the float in the jar you might have to just tweek the fingers so the needle shuts off with the fuel at the same level as the 3/16 method would have given you but with the float down a bit due to weight, you would already be turning the fuel tap off as soon as you pull up I'm guessing as you would be aware they are prone to not sealing everytime. I might see if I can locate an unmolested float, got time on my hands.
  • Merv
    Merv
    2 days ago
    Yes, what you say is what I need do. Only problem is I don't know how much fuel should be in the bowl using the 3/16" rule. That's the missing bit of info. Really appreciate it if you have a good float you are willing to part with. I have a new needle coming from the US.
  • Hilly
    Hilly
    2 days ago
    Quoting Hilly on 29 Sep 2025 08:41 AMedited: 29 Sep 2025 09:38 AM

    https://ebay.us/m/zAUaRx

    The float looks ok on this one, hard to be sure of course.

    The link below is a good read on your float dilemma, my thoughts are as you have 3 wheels the level is not going to change much so I'd set it so it's low enough not to go where it's not ment to and high enough that it doesn't run dry when you stay on the throttle, I'm swinging in the dark a bit as I've never had to do what you are doing.

    Quoting Merv on 29 Sep 2025 10:28 AM

    Ha! Thanks heaps Hilly! I couldn't click 'Buy it now' button quick enough on that. Been scouring eBay every night for something like that, so don't know how I missed that on. Will look at both the links in the morning. No idea how much I appreciate your help. Might be getting closer to enjoying my Ironhead yet.

    Happy to help Merv, price was right on that cab wasn't it lol.
  • obisteve
    obisteve
    9 hours ago
    Quoting obisteve on 24 Sep 2025 09:56 AM

    And when it's back together, could you please post a pic of it?

    Some of us on here like Sportsters a lot.
    My records indicate that 1973 was the first year for the Bendix, but the Sportsterpedia should be able to confirm or deny that.

    Quoting Merv on 24 Sep 2025 10:28 PM

    I'm an 81yo amputee. This should keep me in the saddle for the next 10 years or so.

    20250908_125038_resized.jpg
    20250908_125100_resized.jpg
    20250908_125112_resized.jpg
    Well I wasn't expecting that Merv, thanks for posting the pics.
    Great looking trike, good solution to your life situation.
    With the fuel level questions, if the float it the eBay purchase is in good condition, run with that at the 3/16" and be happy.
    Great price too.
    I reckon you might be overthinking issues with your current float though. It will be a little bit heavier from the soldering so will sit a little bit lower in the bowl, so I suggest bending the tang that presses up on the base of the needle up by a precise milliflyshit. It won't have to be much.
    When you get to road testing, do full throttle runs in top from 80kph and see if you get progressive fuel starvation symptoms. If you do, bend it down slightly more. It just has to be positioned that it flows enough to keep up with maximum consumption.
    The fuel is being sucked up through both jets from the well in the bottom of the bowl, the difference in fuel pressure down there from the fuel depth in the bowl being a bit different from very slight differences in float bowl height is stuff all. You're not Jerry Branch preparing it to run at Bonneville after all.
    The usual full throttle run in top, kill the ignition and coast to a stop then check plug colour will still be usefull.
    As Hilly said, it's not going to flood when you lean it over on the sidestand.
    A couple of other things, if you follow the link Hilly provided over to a Bendix discussion on another place and you see posts by a bloke posting as Ferrous Head, this bloke really knows his stuff with Iron heads in Australian conditions under extreme use.
    As well, your original question about the holes through to the carb mounting flange, I reckon they aren't an unused feature of the Bendix, just a relic of the manufacturing process, the top one provides the fuel flow from the top of the needle above the main jet in to the low speed jet. It doesn't need to have a brass check ball pressed in because it's blanked off at the manifold flange, and leaving it unplugged makes for easier solvent cleaning. Been a long time since I've held a Bendix in my hand so I can't say with certainty what the bottom hole aligns with, but reckon it's something similar.
    Anyway, it's a beautiful machine; I hope it serves you long and well, and puts a smile on you face every time you go near it.

  • Merv
    Merv
    8 hours ago
    obisteve, thanks for the reply, and I agree a small difference in the fuel height won't make a big difference, but I do believe that fuel height has more importance than a lot of guys seem to think. As the air flowing thru the venturi sucks the fuel up, too high and will run rich, too low and will run lean. I have tried my existing setup at several levels, with the mixture screw in small increments from too lean to too rich, but still can't get it to 'pull'. Have replaced a good coil, good condenser, good plugs, gasket/O ring kit in carby, and even tho the carby appeared clean when removed, it still spent 2 hours in the ultrasonic cleaner at 50c. So at this point I'll wait for the new needle, and the replacement float. Plan is to then replace points (that's 100% electric bangs), remove the manifolds and install new O rings, another new carby kit. And if I can't get it by then, I shall give up. Been around old motorbikes and cars for best part of 70 years, and this is the first time I've created a problem I can't seem to fix.
  • Merv
    Merv
    3 hours ago
    What I can't understand is that no matter how lean I run it, when I pull the plugs they are always sooty black! I expect to see a light colour. This bike was running great for about 30 or 40 miles when I got it, however it started to run rough, and because it had been sitting for an unknown number of years, and because the filter was full of black stuff like cocky crap, I pulled the carby to clean it, as well as flushed the tank, new fuel filter, etc. And it hasn't liked me since. I get it starting easily, idling beautifully, very responsive to blips of the throttle, however when test riding, not even able to get into 2nd gear. It falters and misses, and backfires as if running lean, but plugs will be sooty. So will leave for 2 or 3 weeks til all the bits are here. Still got a few other bikes I can ride. Time will sort it out. And while waiting, I'll study up on the workings of the carby.


Topics
1/2