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motokid338

Air- fuel mixture

8 posts in this topic

does anyone how many turns from the start the air- fuel mixture screw on a 03 yz450f is supposed to be at :thumbsup:

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On pumper carbs like the modern four strokes have it's called a fuel screw and it should be 1 1/2 turns out. You can fine tune it from there if you experience any popping on deceleration. Don't go further than 2 1/2 turns out because you run the risk of the fuel screw falling out due to lack of spring tension on fuel screw. If you ever do take it out, make sure you have a rag under the carb to catch the oring and spring that are part of the fuel screw...

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im not familair with yz's :thumbsup: i had a ttr so everything is new and diffrent.

but i have the screw turned two turns from the end is that standard or should that be farther out

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im not familair with yz's :thumbsup: i had a ttr so everything is new and diffrent.

but i have the screw turned two turns from the end is that standard or should that be farther out

You should turn it all the way in so it won't go in anymore, then unscrew it from there...always start closed, then open it up.

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Ok start up the bike with a slightly high idle, find the spot with the air screw where the engine wants to die, then back the screw out from that point until the engine hits peak revs. Leave it there. That is how I do it.

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I would but, IF i can get the bike started it wont idle at all as soon as i let go of the throttle it dies

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