Linkert m74b rebuild

[T. Cotten]

Please think about it Louis!

How could removing material close a gap?
The disc should be precisely beveled on its edge to nine degrees, to close properly in the middle of the bleeds. It also has 'facets' on both sides to narrow its edge precisely at the bleeds.

A perfect disc for an un-worn bore would be ~1.5625", measured at the throttle axis. (Please remember that the beveled edge makes the 'disc' oval.)
NOS samples are invariably smaller, probably for two reasons: First, they were probably "seconds", and secondly, a perfect disc will not seal perfectly unless the body is honed while stressed, and then installed under stress!

...Cotten
PS: Please make certain your vendor will accept returns..

[lrcormier]

I plan on ordering a new 9X disc from Into The Wilderness, they appear to specialize on linkert parts and rebuilding on then see how well it seals, I don't see any noticeable eye brow, maybe just very slight. I do have access to a couple fully equipped machinist in San Diego but would rather avoid the complete hone and rebuild with oversize parts if I can avoid it. I'm curious though, it would seem that one could make some small modifications to the disc by simply some slight sanding of the areas that make early contact to the body, wouldn't this work?

[T. Cotten]

M841L&R (and probably M17L&R) also used the nozzle seal, Louis!

If you have an 'eyebrow' of wear in the carb bore from the throttledisc, just throwing in a fresh disc will not close up the daylight around it, even if it happens to be "NOS" size. They are "forgiving" if the groove does not extend all the way to the idle bleeds, but will not be all it could be, unless honed and properly fitted with a disc.

(Beware of commercial 'oversize' discs that are grossly oversized!)

....Cotten
PS: Since the disc should never operate fully closed (as Kitabel noted), the cause of wear must blamed upon a combination of slop in the bushings, and vibration.
An aggravation of this wear is caused when over-torqued to the manifold. Distortion occurs at any fastener torque over 13 ft-lbs (7 ft-lbs for 1/4" fasteners).

PPS: Nobody got the mousetrap joke, huh. I might as well go back to Peoria.

[kitabel]

The throttle never fully closes, but the only light should be at 90° to the throttle shaft: at 3 o'clock and 9 o'clock.
Have you found a 9x disc?

[lrcormier]

Thanks for all responses, also got this from Mike at lintertcarbs.com concerning a seal on main nozzle: "Louis,
Palmer is wrong on that. The only carbs that used a seal on the nozzle were the M53 , M53A1 . They have a shoulder in the body they seal against, all other linkerts the nozzle can push right through if the venturi is out, but not those 2 carbs. Mike".

I'm pretty sure I will need a new throttle disc, mine has the wear in tits on top and bottom where the throttle shaft holes are and lots of daylight around perimeter of closed disc. With a new disk installed will I still be able to see some light around the edges or will the bike not idle properly unless there is a perfect seal all around? T.Cotten I also sent you a personal msg.

[T. Cotten]

Sounds a little 'Rube Goldberg

That was so helpful!

Rube was my hero, Kitabel!

(Tell me he didn't inspire the Big Twin hand-clutch.)

If its true that the M53 series used both a fat nozzle seal, and a fat bowl gasket missing from all other side-bowl models, then the float setting should be like 3/16" or so, unlike any other Model M Linkerts. Can anyone confirm or deny this from HD literature?

....Cotten

[kitabel]

Sounds a little 'Rube Goldberg

That was so helpful!

[T. Cotten]

...I've read a suggestion that the bushings and shaft will last longer if you modify the throttle arm by adding a small piece opposite the cable end and use two small springs opposite each other, but pulling in the same direction...

Sounds a little 'Rube Goldberg' to me, Kitabel!

The obvious remedy for short life seemed like baked-on moly disulphide, until everybody said I was too expensive already.

Nobody's got K/Sport literature? (Out of my zodiac too, Folks,.. but its relevant.)

....Cotten

[T. Cotten]

I have only found the nozzle gaskets surviving upon some military models, LRC!

But I routinely cut thin PEEK seals for all, as often there is wear at the spigot or venturi hole. Any leakage at this point defeats the "accelerator sump" function. (Neoprene will not survive modern fuels; Original seals appear either phenolic like Micarta, or an asbestos composite.)

Goodson offers a .250" reamer with extended flutes. The more critical aspect is to keep the bushings aligned with a pilot when pressed in, and to avoid pressing against the bottom of the body's bores. (The pucks I use are counterbored for the bushing slightly to prevent this.)

Most bushings can be installed with very little re-sizing needed; Beware of some modern "stainless" offerings that are already shot out two thou over!
Damaged bodys where the bushings no longer align perfectly will require custom-cut bushings with undersized bores to allow the reamer or hone to correct them.

....Cotten
PS: Does anyone have M53 series literature that should mention seals? Does it also spec a different float setting? Thanks in advance as always...

[ryan]

Both ansi and iso .250" / 1/4" metal cutting drill bits should be made to drill a .250" hole with a tolerance of +.005" -.001"

I am sure folks will chime in, but I personally would use a chucking reamer which can easily be purchased in half thousandth sizes( .0005" ) The reamer will not have a flute span to get both sides at one time. I also do not know what the shaft clearance should be nor the size of the replacement shaft, fully knowing it is around .250"
"I am not sure what size you are drilling up from so this process may or may not work." I chuck the reamer in the drill on the flutes and use the shaft as a pilot which will go both holes, ream the first hole, stop leaving reamer, unchuck reamer, chuck reamer on the shaft on the opposite side, start drill and pull the reamer on through. Do not run reamers in reverse as it will dull them.
If you want both holes to be perfectly in line with each other and held to a certain tolerance, you would have to have your holes honed at an engine builders machine shop.

[lrcormier]

Currently cleaning/rebuilding my LINKERT, and have a couple questions. Palmer's says that main nozzle 27732-50 must be installed with a asbestos or neoprene gasket, I could not find any reference to this gasket in the service manual or parts book? I've ordered a new throttle shaft and bushing kit, not sure if the new shaft will be all I'll need but according to the service manual the bushings should be line reamed using a .250 drill, I'll use the procedure in Palmer's for removal and installation but is there a difference between a .250 drill or 1/4 in drill or is .250 how machinest like to reference them?