What exactly do they do? I mean I know they "Emulsify" the air and fuel of the main jet but why are there so many different settings?
In case of weber, what would the difference be between the F11 tubes and the F16 ones? Do they make the main jet start earlier or later?

stolen from another site:

Cylinder capacity Suggested tube
250-325 F11
275-400 F15
350-475 F9, F16
450-575 F2


as to how they work, from memory, and this mayt be wrong, they are a tube with holes drilled in the sides that mix air and fuel together - I'd need to look in the book for more.

^^ more or less right; reason is so that fuel gets into carb as a vapour rather than little droplets.

[Edited on 5/9/07 by 02GF74]

I`ve got a book By Dan Barton, and at some point he advises not to change emulsion tubes unless you have an engine analyzer.
It also lists a chart with characteristics of each tube, I`ll gather from home and post it later today....

Thanks, does anyone have a guide for del'lorto emulsion tubes?

Hah..
My memory it`s not what it used to be....
Author is Pat Braden.
It does not list any difference between F11 and F16, or F9 for that matter.
Numbers were assignged chronologically.
So theres no correspondence with what they`ll do.
For DCOE, IDA and IDF,
Emulsion Tube action is as follows:
Tube Action
F19 Leaner top end
F2, F3, F14 and F15 Leaner top end and throttle response
F9, F11 and F16 Common usage
F7 Richer low end and Throttle response
F8 richer Throttle response, no change in top end mixture.
Combination of the jet sizes and emulsion tubes, it`s not an exact science, you need to select a baseline and ajust in small increments until you get the performance you are looking for while "reading" the spark plugs to make sure you are not cooking or flooding things inside the engine.
Regards
AA

Muchas Gracias,
tiene cualquier informacion sobre del'lorto?

why didn't you ask about deloorto tubes before?!?!?!

When I was looking in the book to see if it explains how they work, I could have posted the dellorto info!!!


As ^^^ says, the Weber numbers bear no sizing relationship but the dellorto ones do.

No worries, as google is your friend!

Many thanks!!!