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slammmin72

02 YZ426 Jetting

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just bought a YZ426 to add to my collection, and took it to stonyford this past weekend and i noticed that from a start, if u crank the thottle all the way...its just sputters and pops, and doesnt take off unless u back off and ease into the thottle. im am jsut guessing it is a jetting problem becuase it had a White Brothers E-series pipe on it (i installed the Stock one right before the trip becuase of the noise issue) and also im guessing that altitude had somethign to do with it aswell (anywhere from 1100 to 5300 ft). some guy told me to get the Boysen Quickshot Acelerator pump for it...., so i guess my question is, is there a way to adjust my bike with the jets in it (not sure what they are...or exactly where they are in the carb.) and also it has one of those red knob screws on the bottom of the carb...what does that adjust, and which way do u turn it? and how do u know if it is too lean, or too rich? (im a newb to 4 strokes...man this things complicated.....)

thanks

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The red knob is a non stock replacement air/fuel adjustment.

Now, when I went to stonyford (with my 2stroke) I had to open up the air/fuel mix to let more air in because of the elevation.

My suggestion, rotate the knob counterclockwise to allow more air.

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The red knob is a non stock replacement air/fuel adjustment.

My suggestion, rotate the knob counterclockwise to allow more air.

The screw in question is an idle fuel screw, not an air screw. Clockwise (in) is leaner, CCW is richer.

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