An operator-controllable valve opens or closes an idle air bypass passage in a motorcycle, allowing an operator astride the motorcycle to set an idle position manually. A handle permits a first adjustment by the operator without use of a screwdriver or other hand tool. An additional interface enables a wider range of adjustment using a hand tool. Both interfaces vary depth of an air mixture screw of the valve within an idle air bypass passage of a throttle body. Dual cylindrical members of the valve rotate relative to one another and relative to a base of the valve, each cylindrical member driven by one of the interfaces. Locking the cylindrical members together such that both rotate in tandem upon the operator moving the handle is accomplished by either tightening the handle or tightening a nut coupling the handle to the valve. A handlebar adjustment lever may couple with the handle.