Have you removed your idle adjustment screw? Most of these carbs are factory set to keep running at a low idle and stalled by being grounded via a switch. In the boats, we typically remove this screw, usually a large black adjustment screw that you can easily turn with your fingers. By removing that screw, the butterfly is able to completely close thereby shutting down you engine by a forward motion on your throttle trigger once your linkages and/or radio is properly adjusted.