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Many carbs were designed for brass floats, even the Schebler G model for motorcycles, but our "bowl" carbs do best with something much more sensitive.
The float closes the valve because of the force of the fuel displacing it upward. If the float weighs four times as much, it sits very deep in the fluid. Thus the setting must be lowered drastically to get it to shut at the level the carb was metered for.
Suddenly there is not nearly as much fuel in your bowl. Add the fact that the brass floats are made larger than originals in an attempt to lessen their density, and you lose even more reserve volume in your bowl.
The result is that you must go through a great deal of trial and error to find a setting that will be marginal when you open the throttle rapidly and often. (Remember the extended bowls that flat-trackers often used?:http://www.beautyofspeed.com/gallery...ert-bowl01.htm )
The float cycles like a toilet. Ideally it would stay open just enough to allow as much fuel as is being consumed. But in reality it causes brief rich periods and brief lean periods as it actuates.
A very buoyant float gives a very low amplitude cycle, but a heavy float is sluggish with its own inertia. So these periods of rich and lean are amplified enormously. Ever wonder why machines aren't getting the fuel mileage our fathers bragged about?
The heavy mechanism wears quickly upon the pivot lever and pin as well. Fresh hardware can display wear in 2000 miles that can be compared to generations of wear with OEM floats.
The material I use is actually less dense than cork or 'Armstrong' foam. So they are of less volume, and slightly less mass than originals. They can be set to book spec with a ruler and forgotten.
One mystery to me is why folks have reported great results with ultralight floats even when intentionally set drastically high or low. It's almost as if the setting drops out of the equation when the float floats.
....Cotten
The float closes the valve because of the force of the fuel displacing it upward. If the float weighs four times as much, it sits very deep in the fluid. Thus the setting must be lowered drastically to get it to shut at the level the carb was metered for.
Suddenly there is not nearly as much fuel in your bowl. Add the fact that the brass floats are made larger than originals in an attempt to lessen their density, and you lose even more reserve volume in your bowl.
The result is that you must go through a great deal of trial and error to find a setting that will be marginal when you open the throttle rapidly and often. (Remember the extended bowls that flat-trackers often used?:http://www.beautyofspeed.com/gallery...ert-bowl01.htm )
The float cycles like a toilet. Ideally it would stay open just enough to allow as much fuel as is being consumed. But in reality it causes brief rich periods and brief lean periods as it actuates.
A very buoyant float gives a very low amplitude cycle, but a heavy float is sluggish with its own inertia. So these periods of rich and lean are amplified enormously. Ever wonder why machines aren't getting the fuel mileage our fathers bragged about?
The heavy mechanism wears quickly upon the pivot lever and pin as well. Fresh hardware can display wear in 2000 miles that can be compared to generations of wear with OEM floats.
The material I use is actually less dense than cork or 'Armstrong' foam. So they are of less volume, and slightly less mass than originals. They can be set to book spec with a ruler and forgotten.
One mystery to me is why folks have reported great results with ultralight floats even when intentionally set drastically high or low. It's almost as if the setting drops out of the equation when the float floats.
....Cotten
) the little flatty fired up and purred like a kitten. Thanks Cotten!!!
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