| MODEL | LAMBRETTA 125D SERIES 1 1951 |
| Year | 1951 |
| Engine Type | Single cylinder, two-stroke |
| Displacement / Capacity | 123 cc / 7.51 cu in |
| Bore X Stroke | 52 x 58 mm / 2.0 x 2.3 in |
| Compression Ratio | 6.5:1 |
| Cooling System | Air |
| Max Power | 3.6 kW / 5.0 hp @ 4600 rpm |
| Max Torque | — |
| Ignition | Contact breaker and points |
| Induction | Carburettor, Dell'Orto |
| Start System | — |
| TRANSMISSION SPECS | |
| Lubrication | 5% |
| Gear Box | 3-speed |
| Clutch | Hand changed |
| Final Drive | — |
| CHASSIS SPECS | |
| Frame | Tubular steel |
| Front Suspension | — |
| Rear Suspension | — |
| Front Brakes | Expanding (drum) |
| Rear Brakes | Expanding (drum) |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | 69.9 kg / 154 lb |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 4-8 |
| Rear Tyre | 4-8 |
| FUEL SYSTEM | |
| Fuel Capacity | — |
| Fuel Consumption | — |
| Top Speed | 72.4 km/h / 45 mph |
The 125D Series 1 raised compression and output over the earlier 125B and 125C, giving a little more speed from the same 123 cc air-cooled two-stroke. It kept the tubular steel frame, hand-change three-speed gearbox and 8-inch wheels.
