| MODEL | BSA A28, A29 AND A30 1928 - 1930 |
| Year | 1928 - 1930 |
| Engine Type | Two stroke, single cylinder, 3-port |
| Displacement / Capacity | 174 cc / 10.6 cu in |
| Bore X Stroke | 60 x 61.5 mm |
| Compression Ratio | — |
| Cooling System | — |
| Max Power | 1.25 kW / 1.7 hp |
| Max Torque | — |
| Ignition | Magneto |
| Induction | — |
| Start System | Slip-on kick starter |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 2 Speed |
| Clutch | Dry clutch |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Duplex |
| Front Suspension | Single spring girder fork |
| Rear Suspension | None, spring-loaded saddle |
| Front Brakes | None |
| Rear Brakes | Hand lever and foot pedal on rear wheel, internal expanding drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | 711 mm / 28 in (lowest setting, adjustable upwards) |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 2.375 x 24 |
| Rear Tyre | 2.75 x 24 |
| FUEL SYSTEM | |
| Fuel Capacity | — |
| Fuel Consumption | — |
| Top Speed | — |
BSA's first production two-stroke, introduced for 1928 as a cheap, easy-to-ride lightweight. Unlike most rivals using bought-in Villiers engines, it had BSA's own unit engine and two-speed gearbox in a duplex frame, with both brakes working on the rear wheel.
