linkert mileage and performance issues

Linkert related issues
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FlatHeadSix
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linkert mileage and performance issues

#1

Post by FlatHeadSix »

Linkerts don't have an accelerator pump either, and they don't "cough".

(just thought I'd throw that out there to get things stirred up)

sorry

mike

moderators note: this thread was split from a topic on timing issues.

john



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#2

Post by Robert Luland »

That's right Flat six the Linkert didn't cough. But the SU gets a third better gas mileage and doesn't spit at you when you nail it. Constant velocity baby. Cavemas, whatever. I'm not buying it. My buddy Indian Larry or as we called him in the eighties Sporster Larry who has since past ran a Super B on that rat heap of his and for the life of me he could make that thing sing. I mean rocket fast with out a cough or any other problems. That's half the problem. Getting the damm thing jetted properly. I remember riding around with an aspirin bottle full of jets. I don't know. To all of ya that have one and made it work. My hats off to ya. Bob L

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#3

Post by john HD »

FlatHeadSix wrote:Linkerts don't have an accelerator pump either, and they don't "cough".

(just thought I'd throw that out there to get things stirred up)

sorry

mike
and to further stirr stuff up, i believe i am getting excellent mileage with my linkert AND cotten's float. as a former CV carb user i can safely say the throttle response is as good as the CV and the top end might be a little better.

no leaks either!

john

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#4

Post by 51Hog »

What is your MPG? Hwy and City?
I am getting 30mpg Hwy 55-65 mph, and 25mpg city 0-45 mph.
Linkert with Cotton's great float in mine also.

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#5

Post by fourthgear »

Every body's riding habits are diff. , so its hard to compare one rider to another , but saying that , I was getting about 34 mpg with Link & cotten's float , then went to CV 40 & mallory and it went to 52-53 mpg , depending on how I ride her , but pretty constant. Double up I get about 45-46 mpg .

Now every machine has different components in them and there age ( component wise ) may have some thing to do with it .

The Linkert is a good all around carb..

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#6

Post by Robert Luland »

What the hell does a bowl float have to do with gas mileage? This I got to here! If you restore you use the Linkert. If you’re not into restoring it would be the last carb I would pick for the road. Talk about a back yard misfit contraption. Bob L

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#7

Post by john HD »

lemme fill her up again and see what i get.

speedo error might be at play here too...

john

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#8

Post by john HD »

bob,

i can certainly say i would not be running that carb if you had not helped me out with the throttle cable tab a couple of months ago!

i think that cotten's float certainly prevents over filling of the float bowl and wasting gas. that might be where i am seeing better mileage than i expected.

like i said, let me fill her up again and see what i am getting for mileage.

john

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#9

Post by 51Hog »

WOW Bob---You got a tooth ache or somethin????

:-)

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#10

Post by 51Hog »

My speedo is off by 5 mph.
60 indicated is actually 55 mph.
60 miles on the odometer = 55 miles actual.
I get 93 miles on 3 gals. Indicated.
actual miles=85.25
MPG =28.42 adjusted
I ride easy---very few times do I romp on it.
I am also easy on the brakes. I coast a lot while slowing down.

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#11

Post by 51Hog »

Wonder how much of the mpg increase was due to the ignition.
Is your odometer correct? 50 mpg is awesome.
fourthgear wrote:Every body's riding habits are diff. , so its hard to compare one rider to another , but saying that , I was getting about 34 mpg with Link & cotten's float , then went to CV 40 & mallory and it went to 52-53 mpg , depending on how I ride her , but pretty constant. Double up I get about 45-46 mpg .

Now every machine has different components in them and there age ( component wise ) may have some thing to do with it .

The Linkert is a good all around carb..

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#12

Post by Cotten »

Bob L!

Let me first make it clear that my floats are made to reproduce the original, not to improve upon it.
The float cycles like a toilet float. When it is filling, it is producing a lean period. When filled, it produces a rich period. Heavy modern replacements cycle sluggishly, producing extended rich and lean peaks. A light float flattens out the cycles to give more efficient overall performance, thus better fuel mileage.

Your contempt for the original hardware raises the question as to why you have any love for the the rest of the vintage 'contraption'.
If you really feel that the Linkert is "back yard", then please explain how literally hundreds of thousands were produced with a .009" slot cut through .030" casting wall down in the idle bleed pocket that is only 5/16" wide and equally deep. (See attachment)
This can only be practically accomplished today with EDM techniques.

Its easy to distain what you do not understand. If you did, you would marvel at the Linkert. After all, H-D only used it for thirty two years (not counting the DC models.)

If you need modern, go modern.
The rest of us will honor this wonderful heritage.

...Cotten
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#13

Post by FlatHeadSix »

Cotten,
Correct me if I'm wrong, but my understanding of off-idle throttle response in the Linkerts was directly related to the size and height of the holes in the emulsion tube relative to the available level of fuel in the bowl. They were engineered to operate most efficiently (economically) with a certain controlled level of available fuel. If a sluggish float allows the level to fluctuate, high and low, without responding rapidly enough to maintain a constant correct level, the carb will not operate as intended, it will waste fuel when it doesn't close quickly enough to prevent overfilling the float bowl.

My opinion about why the Linkerts work so good is that they were designed and engineered and tested to do just that, work good. I'm sure that the M74B is not an accident, the subtle differences between it and other Linkerts were the result of matching that specific carburetor to the engine so that it met the demands of the average operating conditions of that engine. Venturi size, jet size and everything else were considered so that it would work satisfactorily within its adjustment range.

All the other carburetors that folks try to stick on pans were originally designed to work on some other engine. Unless you have drastically modified your pan engine, seriously changing it from its original configuration, the Linkert should be just fine.

But hey, the original topic of this thread is about timing marks, not carburetors. Correct timing has as much to do with fuel economy and performance as the carb. My opinion on timing marks is that they are there to provide a "starting point". If you have the timing set close enough that you can start the engine reliably, you can fine-tune it from there by "ear" or "feel". I have always bumped it a degree or two at a time increasing the advance until it pings or knocks. You get the best economy with as much advance as your load and driving style will tolerate.

I need a beer.......

mike

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#14

Post by fourthgear »

51hog
My speedo is off about three mph, last I checked , but it could go up or down ( I know my over all mileage total is wrong compared to a Dyna WG. I ride with, he has about the same total miles as me ,but I ride much more and he got his bike about the same week I got mine back on the road.

Electronic ign. (mallory ) I'm sure has a lot to do with it, but the CV type carb. is a very efficient design also . They are just much more efficient designs. I have used a timing light on all electronic ign. I tune with the mark dead in the middle,I have always used it for a reference ,works so good on this motor , I'm not going to play with it .

Another thing about the ign. ,all I do is change plugs once a year . I do put the timing light on once in awhile just for curiosity , the mark has not moved since I installed the Mallory a couple of years ago .

I'll say this for Cotten's float , after installing it , I never had to worry about shutting my fuel valve off ( how much hard starting is caused by excess fuel in the manifold after shut down )and the carb did perform better .

These posts always wonder around , you should know this , we be chatting , right .

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#15

Post by Cotten »

Mike!

If "off-idle" performance means that difficult range of RPM between idle and power band, I believe it has more to do with the idle bleed holes than the main nozzle ('emulsion tube'), but obviously everything overlaps.

It would be best to start a new thread to delve into carb theory; It could go on forever....

Back to timing marks,
Anyone who has tried to time a Chief will find new respect and love for H-D's precision indexing!

....Cotten

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