| MODEL | BSA 7.70 HP V-TWIN 770 1928 |
| Year | 1928 |
| Engine Type | Four-stroke V-twin side-valve |
| Displacement / Capacity | 770 cc |
| Bore X Stroke | 76 mm x 85 mm |
| Compression Ratio | — |
| Cooling System | — |
| Max Power | — |
| Max Torque | — |
| Ignition | Chain-driven magneto |
| Induction | Amac carburettor |
| Start System | — |
| TRANSMISSION SPECS | |
| Lubrication | Gravity feed to a mechanical pump with sight feed to the crankcase, hand pump for emergencies |
| Gear Box | BSA three-speed, constant mesh, enclosed kick-starter |
| Clutch | Floating dry-plate, left-hand lever |
| Final Drive | Chain: front 1/2 x 0.305 in, rear 5/8 x 3/8 in |
| CHASSIS SPECS | |
| Frame | Weldless steel tube with forged lugs, sidecar lugs, steering damper |
| Front Suspension | BSA spring fork with barrel spring and shock absorbers |
| Rear Suspension | — |
| Front Brakes | Internal expanding, 7 in, right-hand lever |
| Rear Brakes | Internal expanding, 7 in, heel pedal |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 26 x 3.25 in Dunlop cord (27 x 4 in balloon optional) |
| Rear Tyre | 26 x 3.25 in Dunlop cord (27 x 4 in balloon optional) |
| FUEL SYSTEM | |
| Fuel Capacity | 1 7/8 Imperial gal (De Luxe 2.5 gal; oil 3 pints) |
| Fuel Consumption | — |
| Top Speed | — |
A mid-sized side-valve V-twin offered in a lighter solo-oriented form and a heavier De Luxe aimed at sidecar touring. It gave the smooth running and reserve power typical of a twin.
