| MODEL | BSA B25, B25SS, B25T & FLEETSTAR 1969 - 1970 |
| Year | 1969 - 1970 |
| Engine Type | Single cylinder, four-stroke, OHV |
| Displacement / Capacity | 249 cc / 15.2 cu in |
| Bore X Stroke | 67 x 70 mm |
| Compression Ratio | 10:1 (Fleetstar 8.5:1) |
| Cooling System | Air cooled |
| Max Power | 19 kW / 25.8 hp @ 7250 rpm |
| Max Torque | — |
| Ignition | Coil |
| Induction | Amal Concentric 928/20 |
| Start System | Kick start |
| TRANSMISSION SPECS | |
| Lubrication | Wet sump |
| Gear Box | 4-speed constant mesh |
| Clutch | Multi-plate, integral cush drive |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | — |
| Rear Suspension | — |
| Front Brakes | SS/T: 6 x 0.875 in drum, single leading shoe; Fleetstar: 8 x 1.5 in twin leading shoe drum |
| Rear Brakes | 7 x 1.125 in drum, single leading shoe |
| DIMENSION SPECS | |
| Overall Length | 2160 mm / 85.0 in |
| Overall Width | 737 mm / 29.0 in |
| Overall Height | 1105 mm / 42.5 in |
| Seat Height | 810 mm / 32 in |
| Wheelbase | 1370 mm / 54 in |
| Ground Clearance | SS/Fleetstar 178 mm / 7 in; T 190 mm / 7.5 in |
| Dry Weight | — |
| Wet Weight | SS/Fleetstar 131.5 kg / 290 lb; T 130.2 kg / 287 lb |
| WHEEL SPECS | |
| Front Tyre | SS/Fleetstar 3.25 x 18; T 3.00 x 20 |
| Rear Tyre | SS/Fleetstar 3.50 x 18; T 4.00 x 18 |
| FUEL SYSTEM | |
| Fuel Capacity | SS/Fleetstar 13.5 Litres / 3.5 US gal; T 9 Litres / 2.5 US gal |
| Fuel Consumption | — |
| Top Speed | 135 km/h / 84 mph |
The last of BSA's unit-construction 250 singles, grouped here as the road-sports SS, the off-road T and the Fleetstar. The SS and T are the sporting roadster and trail versions, while the Fleetstar is a milder, lower-compression model built for fleet and police buyers. Based on the C15 engine, the family earned a reputation for big-end and conrod failures, which the oil-in-frame redesign tried to fix before the 250s ended.
