Hi everyone! I just want to share my experience about fitting a single 40 DCOE Weber carb on a COMPLETELY STOCK A15 economy version(round port head). Baseline settings should be: Main Venturi 32; Aux. Venturi 4-5; Main Jet 130; Emulsion Tube F-11; Air Corrector Jet 180; Accel. Pump Jet 40; Accel. Pump Inlet Valve with Ex. Orifice closed; Needle Valve 200. Idle Jet 55F8 In my case, this set up increased torque, throttle response and fuel economy when compared to the factory Hitachi carb. Hope this is helpful.