Calling All Linkert Owners, Part 2.

[1964 pan]

Where are you running the low and high speed needles? Cam, exhaust and geographic location will make a difference. I am running stock cam, 2 into 1 header pipes into a standard "rocket muffler", am in Central Texas. Manual says 5 turns out on low speed. Will be rich. I am running 4-1/8 turns out on low speed. Working for me. On high speed needle manual says 2 turns out. Then it says high speed is metered by a fixed jet. High speed needle is a "trimmer valve". To supplement fuel during extremely high speed operation. That is not me. So? Just leave high speed needle at 2 turns out? Where are you running high speed needle?

[john HD]

how do your plugs look? i assume yours is a FLH.

i run mine at about the same, 3 1/2 low 1 3/4 on the high.

mine is a 55 FL with stock aircleaner and exhaust.

john

[Cotten]

1964 pan!

It does not matter where others have their needles set;
It only matters where yours performs the best.

The manual's suggestions are for initial start up, and attempt to accomodate imperfect conditions.
When all things are in order, including the manifold, the five turns out on the lowspeed can be too rich to idle at all.
And the highspeed needle upon the M-74B is notoriously insensitive.

I ship them back at 3/4 of a turn on the highspeed, and 3 1/2 turns on the low.

....Cotten

[CaptMike]

My bike seems to always run rich.

It's easy to identify where the "Sweet Spot" is. When adjusting the idle needle, I have about 5 Clicks that are less than 1/2 of the others (or almost worn out).

[58flh]

I have always found it best to ADJ. at operating temp.!--& at 2000rpm!---EVEN then it has to be tweaked some until both are in that sweetspot that CAP! is talking about!----EVERY rngine is DIFF. as COTTON said!---BUT for starting & im at sealevel -2 turns out on both will start the bike! BUT there is more tuning left to do!. Sometimes I do them while going down the road!-Always keeping track of the clicks on power & Idle circuit.--CRUDE BUT I be DAMMED if those bikes are not 1-2 kick & go! & I dle great!--JUST my 2----RICHIE

[Cotten]

Folks,

When dialing in the needles to their sweetspots,
a few things must be kept in mind.

The highspeed can only be adjusted on the highway.
All changes should be incremental, allowing time for the circuits to come to equilibrium
The high and lowspeed circuits do not overlap, but the effects of their needles do.
The lowspeed circuit reverses itself when enough velocity through the venturi causes enough draw to enable the highspeed circuit. Thus an apparent "rich" setting upon a lowspeed needle is a lean setting for the highspeed, as it meters air instead of fuel, in reverse.

The highspeed needle of the M74 series is a fraction of the size of models that do not use a fixed jet (military excluded).
The fixed jet supplys the motors basic needs, and the needle only augments it slightly. At high altitudes, it may suit to shut it completely.

It is easy to forget that bowl itself is a third circuit, since simple book spec is the only adjustment.
Conditions within the carb include borewear from the throttledisc, the fit of the venturi, the fit of the nozzle spigot within it, the needlepoints and their seats, the chokeshaft play within the casting, the chokecam and lift linkage,.... even the spring within the lowspeed needle's knob can cause consternation if not firm enough.

Another parameter that I have suspect greatly is the lowspeed needles lift-lever spring collar seat upon the body. The spring collar hole is a metering orifice for air.
If the seat upon the body is not flat, it will allow leakage, as well as prevent the collar from sliding properly, causing wear upon the needle and orifice.

352SEAT.jpg

And finally,There was a time when plug reading was a valuable tool, but then along came fuel with deposit inhibitors. What dials in sweet may leave plugs appearing starved, without harm.

....Cotten

[1964 pan]

Although I have had my 1964 Pan since 1974. For reasons I won't go into I have run a Shovel top end for about 35 years. Just recently I have got a Pan top end back on it. Tried a S&S Shorty E that I had. Was a bear to start and keep running. I still have the M74 that was on it when I got it. So. I cleaned it up put some gaskets on it and put it on. Best damn carburetor ever made. Starts and runs like a Pan is supposed to.
Just trying to build a little knowledge base and consensus about it. That is what this internet thing is about. Thanks for the input.

[john HD]

just out of curiosity, what are you running for a float?

i have one of cotten's floats in each of my bikes and a couple in friends bikes too. simply put, his float is the best thing i ever did for each of them!

john

[George Greer]

i have one of cotten's floats in each of my bikes and a couple in friends bikes too. simply put, his float is the best thing i ever did for each of them!

john

I'll have to give a AMEN on that one John.

George