Schebler HX181

[indianut]

I am in need of some advice. I am working on a 1925 HD FE and am messing with a Scheb HX for the first time. The bike has not run in years. The carb measures 1 3/8" at the Bore. Here are my questions.
1 There is a worn groove in the bore from the throttle plate, but the way it looks to me like the Idle Circuit works maybe that will not be as much of a problem as a later Scheb or a Linkert?
2 The bowl nut has a hole in it and I see there is some kind of elbow tube supposed to attach there. I guess, unlike a Linkert the fuel level in the bowl is BELOW the Nozzle Tube(?) so it will not pour out. How important is the Elbow Tube?
3 There is a groove in the strap that lifts the Adjustment Needle, and there is NO wheel on the arm. The arm just rides on the strap and seems to move up and down OK. Should this be fixed and where might I find these parts?
4 There is no leather disc on the Choke(?) disc, but the steel disc seems to close well enough. With the disc set in the Run position there is no spring tension and the disc is about 3/16" off the throat. Is this Close to right.
5 The Nozzle(?) looks boogered up but appears good and intace on the inside of the Body.
Sorry for all the questions, but when I get this one sorted out the next one will be easier as I will Kinda know what I am doing!
Also, the Mag Gear has what appears top be a factory mark in it and another Wider mark that was aligned for timing this engine. The odd thing is that a Male Tooth is required to line the marks, and that is what the Home Made(?) mark is where the Factory(?) mark is on a Female tooth. I am posting a couple of pics as well. Thanks in Advance.

[T. Cotten]

I am in need of some advice. I am working on a 1925 HD FE and am messing with a Scheb HX for the first time. The bike has not run in years. The carb measures 1 3/8" at the Bore. Here are my questions.
1 There is a worn groove in the bore from the throttle plate, but the way it looks to me like the Idle Circuit works maybe that will not be as much of a problem as a later Scheb or a Linkert?
2 The bowl nut has a hole in it and I see there is some kind of elbow tube supposed to attach there. I guess, unlike a Linkert the fuel level in the bowl is BELOW the Nozzle Tube(?) so it will not pour out. How important is the Elbow Tube?
3 There is a groove in the strap that lifts the Adjustment Needle, and there is NO wheel on the arm. The arm just rides on the strap and seems to move up and down OK. Should this be fixed and where might I find these parts?
4 There is no leather disc on the Choke(?) disc, but the steel disc seems to close well enough. With the disc set in the Run position there is no spring tension and the disc is about 3/16" off the throat. Is this Close to right.
5 The Nozzle(?) looks boogered up but appears good and intace on the inside of the Body.
Sorry for all the questions, but when I get this one sorted out the next one will be easier as I will Kinda know what I am doing!
Also, the Mag Gear has what appears top be a factory mark in it and another Wider mark that was aligned for timing this engine. The odd thing is that a Male Tooth is required to line the marks, and that is what the Home Made(?) mark is where the Factory(?) mark is on a Female tooth. I am posting a couple of pics as well. Thanks in Advance.

Indianut!

I am only a student of these things, and they still do not make sense to me, but here's what I have conjured...

(1) DLXs and Linkerts often show incredibly deep bore grooves (particularly potmetal Four carbs), but still manage to allow the machine to be punished further. With the H model's airgap to the screw being the only limiter, I suspect that wear would be more critical. But they have come across my benches with the Grand Canyon dug by throttleshafts with enormous slop.
Both designs are amazingly forgiving.

(2) The bowlnut goes all the way through because air comes up the bowlstem. It is not a sump like the DLX design.
Some models, like the Prince, did not have the bottom horn.

(3) The cam strip is probably phosphor bronze. I wish I had some.
The watchmaker blood in you shall prove itself to replace it. (Attached)
You may find it satisfactory to just file, stone, or dress the track in the cam so that the new follower can make its own!

Some discussion of the lift lever and follower can be found just a few threads previously in this forum catagory. (second attachment)

(4) You need the 3/16" leather at least, although modern rebuilders use teflon or PEEK.
Its angle should be cut while mounted and centered upon the airvalve carrier. The carrier bushing and probably the shaft should be renewed, of course, and the airhorn seat re-cut as well. (Third attachment, with a new carrier machined in same set-up).
Spring tension has been addressed in this forum as well, with critical data from "Tommo".

(Unfortunately, I keep encountering examples that don't fall in line. There are at least four different springs, and therefore tensions, and it wouldn't surprise me if there are a dozen.)

(5) All nozzles look like that. The critical interface is inside, and even my arthroscope can't see it.

Mag gears are a real problem when they are harder than the Hubs of Hell, and nearly impossible to drill. If yours lines up where it is already drilled, praise Providence.

More if I can outwit this evil site format,

.....Cotten

[Tommo]

Holy Hell! you're going to have to be patient with this old one finger typist as all the questions you've both asked are going to take me more than one reply to answer.
I'm sure all the above questions have been asked on this forum before and have received comprehensive replys but my limited computor skills don't seem to enable me to find them so here goes.
With a Model H if you want a nice regular idle and easy starting you must eliminate as many air leaks as possible.
The following are places where wear occurs and lets in excess air:
Carb to manifold mounting faces
Throttle shaft
Butterfly to carb throat
Air valve disc to air horn seat
Air valve disc carrier to choke rod shaft
and if slip jaw pliers have been used in a brutal way to remove or replace the air horn air leaks can occur where the air horn screws into the main carb body.
All these places need to be restored to factory specs if good idling and starting are to be achieved.

The main jet nozzle is screwed into place then ground to clear the float and soldered into place by the Schebler factory. Unless you are absolutely sure that something is seriously wrong with it DO NOT UNDER ANY CIRCUMSTANCES TRY TO REMOVE IT!
Factory replacement jets are blind and once you have put a new one in you need to come down from the top and drill the correct size hole in it so the needle will go into the hole correctly when it's screwed in. It's a swine of a job and should be avoided at all costs if that is possible. Maybe Cotton wants to learn to do this one because I'm not volunteering. Been there, done that.

Back to the throttle disc and chatter marks in the venturi, because the idle speed screw, which appears as a rod sticking out the side of the venturi into a notch in the butterfly, controls the air bypassing the butterfly any extra air in this area tends to raise the idle speed and in the worst cases it is sometimes not possible to get enough adjustment to control the idle. It's up to the individual as to whether or not you repair this damage or not but as I find all carbs that I see will have throttle shafts that need attention it's best to do the carb venturi and make a butterfly to suit while you have the throttle shaft out.
All Model H carbs have a soldered in butterfly so once you have it out its best to convert it to a screw mount like what is in the DLX series carbs and this modification makes it a lot easier to centralise the butterfly in the venturi when you replace it.

The idea of the air horn on the bottom of the bowl stem was to supply heated air up into the carb to assist in fuel vapourisation but modern thinking is more towards cold air. The bike will run beautifully with or without it.

The cam track and cam follower have been discussed not that long ago and as there are two types of followers I need to know which one you have.
The early type, which has a wheel, will have a small threaded hole at the end that is at right angles to the main stem.
The later type has a fibre rubbing block that goes into a hole that is drilled into the end of the stem.
If you've got the early type with the wheel and the track the wheel runs on is too badly grooved you can generally make a new wheel with a wider than standard face so that it bridges the groove and runs on the unworn surface above and below the groove.
Thats enough for now and please excuse any spelling errors as I've not proof read what I've written.
Next installment will be the air valve.

[Tommo]

Re replacement parts for HX series carbs.
The following parts are being made or have been made and will be available for sale in the near future.
Float needle.
Knurlled cover cap that allows access to the float needle.
Cam track and its two mounting screws.
The extra air trapdoor and its mounting screw.
7/16 x 27 t.p.i. Fuel line nuts and the bullnose that is soldered to the fuel pipe. ( the bullnose is available in two sizes one to suit Indian and the other to suit Harley)
15/32 x 24 t.p.i. Fuel line nut and bullnose to suit Harley fuel taps.
Air valve springs in varying strengths.
I do have a limited number of nos Needle jet thimbles and the early style cam track assemblies that have the adjustable lever at one end.
I'll post about the air valve tonight after work.

[exeric]

I think an HX 181 is intended for a 74". An FE is a 61". Did the owner say how it ran on 1 3/8" carb?

[MMasa]

I think that your mag gear is off of an Indian. It looks like the keyway is half round and not square. Didn't Indians use a dowel as a mag gear key?
Mark Masa

[indianut]

Thanks to EVERYONE for the Excellent help. Please keep it coming. Eric, he has owned the bike for 25 years and never ridden it. Yesterday I made a new Rod shaft and Honed the bore. I am doing the disc today out or either Peek or Teflon. I will post more pics tonight. Thanks Again. Cotten....Very Impressive Memory RE the Watchmaker Blood!

[indianut]

I am a little unclear about the air valve (Leather) piece. This is the Only carb like this I have worked on so I have no reference point. If I understand Cotten's pic the valve (leather) is squeezed between washers and on a mandrel that slides on the shaft. Could it even be one piece of Teflon or Peek with a bushing. Or maybe I am seeing the pic wrong anyways. Here is all I have to go by.

[Tommo]

The air horn is the most important part of a Model H and is what gives the carb the bad name it does not deserve.
The disc and its seat works just like any valve and seat and for best performance needs to seal perfectly.
Leather tends to dry out and crack and warp so the use of a modern material is preferable.
The disc carrier slides on the choke shaft and the choke shaft moves in the mixture adjusting nut, (this nut is notched and also serves as the choke ramps,) so all these surfaces wear and create air leaks.
If you are going to use your existing mixture/ choke nut you need to ream this out first then make a choke shaft to suit the bore of the nut and then make a disc carrier to suit the choke shaft.
All these surfaces need to be a neat sliding fit and the disc carrier especially must not bind at any place along it's travel.
Air valve tension springs come in at least 4 different designs and each design comes in about as many lengths. Most springs are either conical or parallel with a rounded in top.
I'm not an expert here but am told by others that these designs tend to keep the pressure constant rather than an increasing pressure you get with a normal parallel spring. Can anybody out there elaborate on this?
We set the air valve up with a 4 ounce seat pressure and this generally guarantees that the bike will start and once it is running you will need to adjust the spring tension to get the right throttle response and high speed mixture.
Is this the sort of info you want or am I wasting my time.

[indianut]

Tommo, this is Exactly the sort of info I am in need of. I have to service several of these carbs in the next few months so I need to fill my Brain! Thanks Eric for the pics of the stock setup, so i have a better idea of what I need. Cotten, I am sorry for so Blatantly Stealing your idea, but it seems to be an Excellent one. I basically copied it today after Honing the bore and making a new shaft in the 'End Housing'. Next is the Float, and the 'Strap/Cam Follower', and 'Strap/Cam' I still have not decided to do with the Body Bore and Disc.

[rwm]

one of these gears is jd and one is jdh

[exeric]

That looks great Danny. I recall Cotten posted pictures of a set-up he devised for measuring the sping tension.

[T. Cotten]

Indianut!

You've got newer equipment than I.

Tommo!

I hope to start a new discussion about the various airvalve springs, as they have me hung up at the moment.
(It may take a while, as jumping to an older machine is the only way I can post pics, and it takes forever.)

And to compare Indian mag gears with Rob's, I shall attempt to upload those first,

....Cotten

[indianut]

Indianut!

You've got newer equipment than I.


....Cotten

Heck...mine came over on the Mayflower.......yours must have come on the Arc!

[T. Cotten]

Indianut!

Attached are early 30's indian mag drive gears for comparison.

I hope to start a new Schebler thread when the electrons allow it...

.....Cotten