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JDrooster

Fuel Screw question

6 posts in this topic

I know this has probably been answered before, but I couldn't find the specific answer using search. It has to do with fuel screw adjustment. Is it similar to how a 2-stroke air screw works? I mean closed = leaner, open = richer. If I have the fuel screw more than 2 turns out, does that mean I need a bigger pilot jet? Any help you all can provide will be appreciated. Thanks. -Jerry

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A 2 stroke has an air screw and the further out you go the leaner the mixture is. The thumper is a fuel screw and the further out you go the richer the mixture is. Look at the sticky on the top of the jetting forum. :thumbsup:

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Thanks guys. I noticed that after the GYTR insert, the header is glowing red more often, and further down the header. I think I need to richen things up for sure. Thanks again. -Jerry

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I know this has probably been answered before, but I couldn't find the specific answer using search. It has to do with fuel screw adjustment. Is it similar to how a 2-stroke air screw works? I mean closed = leaner, open = richer. If I have the fuel screw more than 2 turns out, does that mean I need a bigger pilot jet? Any help you all can provide will be appreciated. Thanks. -Jerry

No, its just the opposite of an air screw. Usually rule of thumb, if the pilot circuit adjustment is behind the slide, its an air screw, and turning it in makes it richer. While the fuel screw is in front of the slide, turning it in makes it leaner. One controls air, other controls fuel. Both are on the same circuit, just different locations in the circuit.

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some 2 strokes have fuel screws and others have air screws, all depends on the design of the carb. Turn out a fuel screw to let more fuel in, turn out an air screw to let more air in...

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