inlet nipple

[T. Cotten]

Poorbiker!

Be carefull where you "fill 'er up": (attached).

....Cotten

[poorbiker]

Well did thorough check on carb, carb to manifold flange is straight and flat, m-74, #19 fixed jet, blew all passage ways out, checked all screws, needles, throttle plate, float,

Found float set at 5/16" not the 1/4" I thought I set it at, its a foam float, it works well. Its not the stock float obviously so I hope the 1/4" measurement still works when I reset it.
Still have to check float valve to float lever, maybe that setting is wrong causing a lean condition and maybe the hesitation I feel at steady speed?

Throttle shaft seems a tad loose but honestly not sure what the fit should be.

Manifold flange is straight and flat.

Not sure what else to check on carb.

Re-set magneto timing, it was right on.

Heads were done by Paul Hannon of Hannons Machine in Oakland, he is like the old guru guy for anything knuckle, especially heads, seats redone, new valves and sportster beehive springs, Paul has been do the spring thing for yrs. Paul did all of Arlen Nesses machine work back in the day, they were on the same street in those days.

[T. Cotten]

Poorbiker!

Both flanges are best inspected by swiping them in a criss-cross pattern upon a large stone, or stick-on abrasive disc upon thick glass. (Straight-edges are futile, unless distortion is extreme, such as the first attachment.)

Please note that re-stallation should not exceed 13 ft-lbs of bolt torque, especially if a -48 spacer is used. (Second attachment is an example where a fellow severely over-torqued, requiring the flanges to be pressed back before another grind.)

From there we must go on to internal issues within the carburetor, such as the bushing to throttleshaft fit, borewear, venturi fit, etc.
You must rely upon your own thoroughness of observation and attention to detail, of course, but if all things are brought into order, the assembly should perform flawlessly.

....Cotten

[poorbiker]

Well took a closer look at the float valve and lever and float height,

1st, float was at 5/16" though I was sure I had done it right, well I hadnt, found my assy error, I initially had it right on at 1/4" but this time around I found my mistake. While adjusting float height which required several assy and dis-assy I wasnt putting the lever pin screw back in, I thought to speed along the assy/height adjustment. Well after putting screw back in I never re-checked float height, it had of coarse changed, lowering it. Now its right on. Dummy

The second item of concern was the lever finger to needle gap, as it turns out it was huge, I assumed it to be right on and never bothered to check, reset finger to needle gap to about .3th,

Throttle shaft is in need of replacement, bought a shaft and bushing kit from "into the wilderness" should be arriving this week?

Only other item of concern is the fixed jet, its a #19. I pulled it out for a closer inspection, it looks original, the inlet hole looked a bit too big by eye, found the correct number drill and inserted it from the front, lots of slop but snug at exit, I thought that maybe its wore out or messed with, as I continued to inspect jet it turns out it was stepped, going from large (twice the dia) to correct dia. a ways down in the jet, my replacement #18 jet has no such step, same dia. from beginning to end.

Which is correct or does it matter or was this some hotrodders trick......

[T. Cotten]

Poorbiker!

Don't feel bad about doing it twice: My shop charges a full twenty minutes of flat-rate to re-assemble and adjust a Linkert bowl, and that is after all prep work and inspection.
(Please invert the entire carburetor with the bowl upon it without gasket, and then suck upon the valve, to be certain that there is no interference with the bowlstem, or side of the bowl. That's where the real fun begins.
You will know the condition of the valve is good when it makes a tiny *pop* when you pull your tongue off.)

For locking the lever to the float, the most commonly available adhesive that still seems to resist P4gas is Pliobond, (although I use an isocyanate urethane).

And yes, #19s (all that I have readily at hand to inspect) all have a restrictive step on the inboard end for the last .020" or so.
(Folks should beware to always use the butt-end of a drill for inspection. The sharp end is damaging. The original factory "field repair" tools are a torture kit.)
Beware also of aftermarket jets that aren't even close.
(Most properly, a drilled hole should be micro-lapped to size. Originals seem to do fine, even if the screwdriver slot is boogered.)

You're getting there!

...Cotten
PS: Please inspect your new shaft when it arrives for a snug fit of the disc within the slot. A large production of USA-made shafts were cut "fat", causing a bind within fresh bushings when the disc is fastened. Many distributors still are flooded with this inferior stock.
PPS: You mentioned that this is an M-74. If it is not a "B", please note if it has a stepped-tip highspeed needle, rather than one with just one angle.

[poorbiker]

replaced throttle shaft and bushing, reset float level and related issues, did the block off plate and 15 psi, soapy water, no intake leaks, thoroughly checked carb. Reinstalled everything
and started bike, seemed to warm up better and reach idle quicker, adjusted carb, went for a ride, exact same thing, Im very dismayed, feels like its lugging at steady speed, roll on it it does great.

One thing I noticed is this time, I tried adjusting the high speed needle at speed (didnt before cause it didnt feel like it needed it) well no amount of adjustment in or out made any difference in the way the engine performed, off or wide open had no affect on performance.

Pulled carb back off and rechecked for any plugs, restrictions, checked that the needle was seating properly, checked the main nozzle, all air passages. Checked the float again, working properly. I can find nothing wrong. I dont have much wits but Im at my wits end.........................................

[poorbiker]

oh and Cotten,

its a 74 not 74b and I have not been able to find a stepped needle, have only seen one in a book and not sure how much it would really matter, having said that, I mentioned in previous message that the high speed needle adjustment has no affect on engine, runs the same if I turn it off or screw it almost all the way out...........

[T. Cotten]

Poorbiker!

I realize that this is of little solace, but imagine what it would be like to do these things for a living.

Once again, assuming all other things are in order, we now must address deeper into the carburetor itself.

The primary reason for periodic replacement of the bushings and shaft is to prevent the throttledisc from wearing an "eyebrow" groove into the bore of the carb body itself.
WEARFIX.jpg
When this groove is quite deep, not only does too much air flow around the disc no matter how closed the idle screw may allow, it confounds the mixture settings between 'idle' and 'power' (speeds over 30 mph). Thus an optimum setting for idles suffers on the road.

Please inspect for this groove, and for how sweetly the disc will close with the idle screw upon the throttle lever backed out.

Next, hold the carb up to the light, and carefully look for daylight around the venturi.
DAYLIGHT.jpg
A venturi that has shrank over the years to where it will fall though the body is certain to leak around it.

And although you have inspected all passages, please use magnification to be certain that a nearly-invisible glass bead (from who knows where) may have lodged within the idle bleed slot beneath the large plug upon the side of the body.
It occurs far more often than imaginable.
sand.jpg
And although it may seem like picking at straws, please inspect the seat for the lowspeed spring collar, as often it has been either poorly cast, or eroded, defeating the springcollar metering orifice.
65DISHED.jpg
All of these can be remedied, of course.
Any one alone may have minimal effect, but collectively, these wear spots, after decades, give Linkerts a bad name.
(And there are more....)

The stepped M74 needle used a smaller seat cut into the bowslstem, than later "B"s, as shown in the middle:
STEPTIP.jpg
Hard to imagine that is the problem, however!
To run with the HS completely shut, either the fixed jet is sufficient, (such as at high altitudes,.. or fuel is getting into the nozzle well by some other means. Look for factory solder repairs upon the bowlstem, as porosities were common.)

Patience,

....Cotten

[poorbiker]

Cotten,

Well there was issues with the carb that absolutely needed fixing however none of them turned out to be the root cause. I got to thinking about a shovel I once had, I installed this very cool air cleaner on the s&s super E and the engine hated it, wouldnt run for crap, so sometime back I bought this very cool rat air scoop that had been popping up on ebay, did I mention very cool.
Remembering the Shovel I took it off thinking it couldnt possibly be that simple, went for a run, perfect, runs so good I could hardly bring myself to come home. I left to go around the block and ended up putting on about 100 miles.
I had scoop with no element in it facing to the rear, I suppose the air was being pulled back out at speed, I know I cant run it facing forward from experience. Dont know if I should scrap it or try it facing down/up? I know most of you are gonna say scrap it for the correct cleaner, which is what I am gonna have to do I suppose.

Cotten,
as always thanks for the info, I did learn a bit more about Linkerts, carb performs very well, I was pleasantly surprised..................FIXED.................. .................

[T. Cotten]

Whew, Poorbiker!

I was getting worried myself.
Linkerts are SO forgiving: They come in with the venturies in backwards, throttlediscs in backwards, floats that look like big black dumplings,... and the owners often say: Worked fine for years!

....Cotten

[Lownslow]

Cotten,

Well there was issues with the carb that absolutely needed fixing however none of them turned out to be the root cause. I got to thinking about a shovel I once had, I installed this very cool air cleaner on the s&s super E and the engine hated it, wouldnt run for crap, so sometime back I bought this very cool rat air scoop that had been popping up on ebay, did I mention very cool.
Remembering the Shovel I took it off thinking it couldnt possibly be that simple, went for a run, perfect, runs so good I could hardly bring myself to come home. I left to go around the block and ended up putting on about 100 miles.
I had scoop with no element in it facing to the rear, I suppose the air was being pulled back out at speed, I know I cant run it facing forward from experience. Dont know if I should scrap it or try it facing down/up? I know most of you are gonna say scrap it for the correct cleaner, which is what I am gonna have to do I suppose.

Cotten,
as always thanks for the info, I did learn a bit more about Linkerts, carb performs very well, I was pleasantly surprised..................FIXED.................. .................

Learned more useful info myself. Valuable thread!

[Lonnie]

Learned more useful info myself. Valuable thread!

I also! BTW, I always use Tom's floats. I know others who use the other well-know variety but Tom's have served me well. And if I ever have a problem with another Linkert I do believe I shall send it to him. Would be money (and time) well spent, I do believe.