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 50 Needle Valve 200 In my case, this set up increased torque, throttle response and fuel economy when compared to the factory Hitachi carb. Hope this is helpful.