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Throttle Problem

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My 2003 yz250f was idling too high, so while on the trail I turned the throttle stop screw, when I started riding again and turned the throttle, the engine just cut out on me. How do I know if the throttle stop screw is back to the right setting. I still have no throttle response. Thx :cry:

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If you're talking about the black knob on the side of the carb, that is the idle setting. Set it so the bike idles at about 2000 RPM.

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:cry:

Turned the "throttle stop screw".....I'm not sure I understand your question. Did you actually pull the cover off and used a hex to turn turn the screw deeper? I'd pull that throttle stop scew out and cut off about 11mm......do the mod! If you're talking about something else, please provide more information.

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Thanks, it is the black knob on the side of the carb. I turned it because the bike was revving too high when in neutral/clutch pulled in. When I began to ride again and turned the throttle and bike sounded like it was bogging down. When I went to start it again, sounded/felt like there wasn't any gas getting to the engine. Not sure if the problem is with the throttle now or if I've screwed up the setting on the carb? :cry:

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Sounds like the bike might be too lean. Have you performed any service on it lately thaty might have allowed an air leak in the intake tract? That's pretty common.

If it hangs at high idle and there are no air leaks, then you might try opening the fuel screw in 1/4 turn increments to see if that helps the problem.

The idle screw (black knob) is to set the idle speed. See your manual for details.

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If you're talking about the black knob on the side of the carb, that is the idle setting. Set it so the bike idles at about 2000 RPM.

This may sounds like a really stupid question but, how do you know exactly what RPM the engine is idling/running at?

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Make sure the clamps are tight on both end of the carb. Check the air boot between the carb and the airbox for cracks and a good seal around the air box. Check the hot start obviously, and any other joints/screws on the carb. You can squirt some starting fluid (ether) at all of these joints with the engine running, and if it speeds up, you've found a leak. Maybe someone else has some other ideas.

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You can get the speed with a cheap inductive tach, or check it by ear, if you've got a reference. I've heard that people have to wrap the inductive tach pickup around the spark plug's coil wire several times to get a sufficient signal, since the coil is right on top of the spark plug.

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