my buddy bought a 400ex and it ended up being a lemon. so he threw in the 440 kit and we just can't seem to get the jetting right. it started out with a 142 jet in it and i narrowed it down to a 137.5 jet and with the plug inspections its in the right range. but the top needle is way too lean and the 4'th slot down is too rich, the quad just has no bottom end power. it burps and pukes 0% to 1/4% throttle. anyone have any ideas? my quad is the same thing with a 440 kit and it uses a 148 jet and its a little rich but it doesn't miss or anything. these quads are almost identical except for the aftermarket exhaust i have.

 

You need to adjust the air screw and use a 40 pilot.

 

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