New Linkert....a few questions

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Aphelion
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New Linkert....a few questions

#1

Post by Aphelion » Sat Feb 26, 2011 9:26 pm

Just finished putting my top end back together on my '60 FLH chop. Spent 20 hours in 2 days slaving away. I replaced the S&S Super E with a freshly rebuild M74b. I did pressure test the manifold around 18psi and got it pretty much perfect.

I turned on the gas for the first start and fuel dumped out of the carb. Re-adjusted my float height and solved that problem.

Got it running and did a couple laps around my neighborhood, but noticed that it was running really rich. Black smoke out of both pipes and strong fuel smell. I turned the idle needle all the way in and it still runs and still smokes. Seems like my #19 jet is way too big because it seems to run best when the idle needle is all the way in...Runs great and really strong at higher rpms, but its super rich at idle and low rpm.

Also, the idle will get pretty high then settle down again....dont know what thats about....

I ordered an 18 and 17 jets but havnt tried them. Any other cause for such a rich condition? This is my first Linkert so im still trying to figure it out.

Possible the carb could have shifted during installation and caused an intake leak....???

And where can I order one of Cotton's floats?!?!
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Cotten
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Re: New Linkert....a few questions

#2

Post by Cotten » Sat Feb 26, 2011 10:02 pm

Aphelion!

At your service: Liberty@npoint.net.

Just a few notes:...

Your manifold is "pretty much perfect"?
18 psi is overkill (14.7 psi is 'equivalent' to total vacuum),
but not even the tiniest blister of foam is acceptible.
If your idle speed varies on its own, you may very well still have one, although it could be within the carb, or even a pancover screw over an intake port.
Did you grind both the carb and manifolds' flanges flat, and the phenolic spacer if it isn't brand new?
Did you line the manifold up to the carb on its support before snugging it down?

You re-adjusted the float height?
There is only one float height: 1/4 inch, and a ruler is plenty accurate enough. If the valve does not seal when the entire carb is inverted, then the float isn't in its "sweet spot", and it can be a real test of patience to find it.

Your lowspeed needle does not control fuel at speeds over ~30 mph. If you can shut it below two turns, something else is amiss.
Is the spring collar in place? Is it's seat eroded, like this:
Dished1.jpg
For an M74* carb, please start with the HS out 3/4 of a turn, and ~4 turns out on the lowspeed. The effect of the needles overlap, so please make adjustments slowly to allow for equilibration of the circuits.

Your assembly may very well have other issues, but Linkerts are very forgiving!

Here to help,

...Cotten
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Aphelion
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Re: New Linkert....a few questions

#3

Post by Aphelion » Sat Feb 26, 2011 10:28 pm

Thanks Cotton, just emailed you about the float.

When I first set the float at 1/4" the valve would not seal. I had to play with the little fingers that hold it to make it work. Float is still set to 1/4".

I got the intake manifold to stop bubbling but after I mounted the carb I had to move the manifold a little bit. I will have to pressure test again.

I did grind the manifold and carb faces on emery paper on plate glass.

The spring collar is there and the seat looks good.

The engine will idle and run with both needles all the way in and still blows black smoke.

My high speed needle is the type with the 90 degree bend in the the top if that makes any difference.

What else could this be?

Cotten
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Re: New Linkert....a few questions

#4

Post by Cotten » Sat Feb 26, 2011 11:45 pm

Aphelion!

I would pretend to be a psychic if I could, honest!

Since we have narrowed it down a bit,
let us consider other common problems:

Wear to the bore from the throttledisc and/or a loose venturi usually result in flat spots upon accelleration, not the symptoms you describe, so I must push them down on the list, for now..

One common and diabolical problem is blasting media in the idle bleed slot. They can be invisible to the casual eye, and show up on my benches all too often:
SLOTBLOK.jpg
Beyond that, we are looking for a supply of fuel that shouldn't be there. A casting porosity is possible, as a great many had solder repairs from the factory, but poor repairs are rare.

In the meantime, I must encourage you to re-inspect your valve adjustment, timing, etc., as they all can all produce a confusing effect.

More when I think of it,

....Cotten
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Panhead Ed
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Re: New Linkert....a few questions

#5

Post by Panhead Ed » Sun Feb 27, 2011 2:24 pm

you didnt mention what air filter are you using..

Aphelion
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Re: New Linkert....a few questions

#6

Post by Aphelion » Mon Feb 28, 2011 12:32 am

Thanks again, ill re-check timing and valves.

As for the filter, i have nothing on there right now, still trying to find something I like.

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Re: New Linkert....a few questions

#7

Post by Bigincher » Mon Feb 28, 2011 1:19 am

Aphelion wrote:Thanks again, ill re-check timing and valves.
As for the filter, i have nothing on there right now, still trying to find something I like.
If I may.... try the stock air cleaner on a stock carb on a stock motor--- it worked in 1960, it should work now.
I've found that the air flow can be different without an air cleaner, maybe you should install the air cleaner.
But in your case, that may compound the problem.....
Respectfully.......

Aphelion
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Re: New Linkert....a few questions

#8

Post by Aphelion » Mon Feb 28, 2011 5:27 am

i dont have a stock filter....

the problem im having is just that its overly rich...air filter shouldnt solve that...if anything it should lean it out with no filter right?

Aphelion
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Re: New Linkert....a few questions

#9

Post by Aphelion » Mon Feb 28, 2011 2:41 pm

Ive been researching this problem all over the web and came up with something that makes sense. Could it be possible, since I have aftermarket needles, that the low speed needle isnt seating all the way in? Or, even that the needle is the wrong one and is too short? Could someone give me a measurement of the low speed needle itself, removed from the holder?

Thanks, I really need to get this sorted out.

UPSROD
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Re: New Linkert....a few questions

#10

Post by UPSROD » Mon Feb 28, 2011 8:19 pm

Aphelion wrote:Ive been researching this problem all over the web and came up with something that makes sense. Could it be possible, since I have aftermarket needles, that the low speed needle isnt seating all the way in? Or, even that the needle is the wrong one and is too short? Could someone give me a measurement of the low speed needle itself, removed from the holder?

Thanks, I really need to get this sorted out.
Aphelion,
Did you possibly put the lock spring below the low speed needle
instead of above it in the lock screw? That would make it very
rich even screwed all the way in.

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Re: New Linkert....a few questions

#11

Post by Cotten » Mon Feb 28, 2011 9:55 pm

Aphelion!

Both the 1 1/2" and 1 1/4" model Ms used a 3.5" long lowspeed needle.

(The 1" model used a 3.125" needle)

Aftermarket needles often are too fat (metric), but not enough to cause a problem, unless it binds within the needle support cast upon the bowlstem.

Beware of a promenent ebay seller pushing re-ground needles as "new", usually with a raw (un-plated) knob, that is so soft the detente ball knarfs its knurl instantly.

Even still, they should still dial in, unless there is an un-ground spot like I found, straight out of the package!

....Cotten

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Re: New Linkert....a few questions

#12

Post by joe » Sun Jan 26, 2014 4:31 pm

I know this thread is old but I have the same problem (the bike runs best with the LS needle screwed all the way in).

Did the original poster ever get this figured out?

Thanks Joe

1956 FLH all stock

Cotten
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Re: New Linkert....a few questions

#13

Post by Cotten » Sun Jan 26, 2014 4:59 pm

Don't know, Joe!

But since then, one fellow who complained to me that he could bottom out his lowspeed found that the spring in the knob was below the head of the needle instead of above it.

....Cotten

UPSROD
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Re: New Linkert....a few questions

#14

Post by UPSROD » Sun Jan 26, 2014 5:09 pm

I said that 3 posts up, 3 years ago!

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Re: New Linkert....a few questions

#15

Post by Cotten » Sun Jan 26, 2014 5:41 pm

UPSROD wrote:I said that 3 posts up, 3 years ago!
Well Rod,...

It happened to somebody again!

Sorry I didn't review the whole thread and quote you, but dial-up time is expensive for me.

....Cotten

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