A40 Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2] A40-2 Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2] A-40-3 Single ignition, 37 hp (28 kW) at 2550 rpm, dry weight 144 lb (65 kg)[2] Featured cadmium-nickel connecting rod bearings.[5] A40-4 Single ignition, 40 hp (30 kW) at 2575 rpm, dry weight 144 lb (65 kg),[2] Steel backed connecting rod inserts A40-5 Dual ignition, 40 hp (30 kW) at 2575 rpm, dry weight 156 lb (71 kg)[3]