Fuel level

[Jarek]

I wonder if there is a description in the literature somewhere of what the fuel level in the carburetor should be

[Steve Slocombe]

Dear Jarek, the literature usually says 5/16" or 8 mm for a cork float below the carburettor bowl edge. This is set by turning the bowl upside down and measuring. I don't know how this translates to actual fuel level, or for foam or brass floats, but I'm sure there is plenty of advice available on this forum.

[T. Cotten]

I wonder if there is a description in the literature somewhere of what the fuel level in the carburetor should be

What model, Jarek?

Flathead Linkerts (and virtually all models except Ks) have a float height specification of ¼", which produces a fuel level of 5/8" within the bowl, with a float of buoyancy equal to OEM.

(No Model M Linkert used a brass float.)

...Cotten
PS: Seriously,
It is difficult enough to get the float at height, level, and offset to clear the bowlstem.

Determining the resulting fuel level isn't as easy as you might think,..
SITGLS13.jpg

so its all about faith in the float.

....Cotten

[Jarek]

What model, Jarek?

Flathead Linkerts (and virtually all models except Ks) have a float height specification of ¼", which produces a fuel level of 5/8" within the bowl, with a float of buoyancy equal to OEM.

(No Model M Linkert used a brass float.)

...Cotten
PS: Seriously,
It is difficult enough to get the float at height, level, and offset to clear the bowlstem.

Determining the resulting fuel level isn't as easy as you might think,..
SITGLS13.jpg

so its all about faith in the float.

....Cotten

Thanks to both of you,

I have Linkert - VL 36. Last season it leaked a little from the bowl, and in the winter I set it as Steve writes 8 mm - 5/16". It seems that now it sucks in more air than fuel and chokes it. It was not a big correction, but still. From my observations it follows that taking into account all the errors related to the float position and others it would be best to set it at the maximum height so that the fuel does not leak from the bowl, but it not easy.
Probably a lot depends on the carburetor

Interesting photo,

[T. Cotten]

The most common reason for a carb to leak, Jarek,

Is a leaky petcock; The bowl will sweat while sitting.

The only excuse to ever set a float deeper than the ¼" spec (6.35mm) is if the float is too heavy. Without the lever and pivotnut/screw, it should weigh three grams or less.

Beware the available fuel volume is only that between the desired 5/8" level and the high speed needle seat, the top two lines:
FUELVOL3.JPG
(More reserve is available if a fixed jet is used, the bottom line.)

Thus if the float is set lower, it displaces available reserve for acceleration. There goes economy and performance..

....Cotten
PS: My sightglass apparatus was necessary for determining and correcting the resulting fuel levels from my various float productions, when compared to NOS examples such as the one shown. With a fuel-resistant float of proper buoyancy, you should be able to just install it to spec and forget it.

The most convenient way to gauge the installation is with a common pocket ruler with two clips:

flotgaug.jpg

The tangs on the clips are ¼", and quickly display the level across both sides of the float.

[Jarek]

I don’t know whether the position of the float is more important for setting the fuel level or to prevent the float from resting against the carburetor body.
If it is positioned too high, it may support itself and not fully close float needle, which could cause leaks.
Of course, a lot depends on the internal diameter and shape.

The float I bought last year in Raalte (Netherlands) weighs 6 grams, but the first one weighed 4 grams.
The float that was in the carburetor when I bought the motorcycle was broken. It was lying loosely in the bowl along with the float needle.

Everything suggests that the previous owner's family deliberately sabotaged it so that he couldn't ride.
The same thing happened with the ignition and a few other components.

IMG_3810.jpeg IMG_3812.jpeg IMG_3811.jpeg

[T. Cotten]

I don’t know whether the position of the float is more important for setting the fuel level or to prevent the float from resting against the carburetor body.
If it is positioned too high, it may support itself and not fully close float needle, which could cause leaks.
Of course, a lot depends on the internal diameter and shape.

The float I bought last year in Raalte (Netherlands) weighs 6 grams, but the first one weighed 4 grams.
The float that was in the carburetor when I bought the motorcycle was broken. It was lying loosely in the bowl along with the float needle.

Everything suggests that the previous owner's family deliberately sabotaged it so that he couldn't ride.
The same thing happened with the ignition and a few other components.

I doubt there was anything deliberate, Jarek!

Just ignorant at best.

The 'sprues' on the bottom of your molded float are not like any I've seen; At twice the weight, its volume was probably increased in a feeble attempt to save a little buoyancy, producing the geometry problems for installation that you are encountering.

The casting gallery you indicate is just one place where even a proper float can hang up, although it is the obstruction that the manuals' "offset" was intended to avoid.:
STEMCST2.jpg
A "dry-erase" marker quickly shows interferences;
The bottom arrow shows a ledge that can be ground away with impunity, as it was eliminated upon later OHV models.

The only way to determine if the float is hanging up upon the bowlstem, or the side of the bowl, is to invert the entire carb and suck upon the fuel inlet. You should detect a tiny 'pop' when you pull your tongue off of it.

Beware that "play" or wear upon the floatlever and/or pivot pin can allow the float to wander. To avoid customer complaints, I die-pressed and re-reamed even the best of aftermarket floatlevers.

....Cotten