| MODEL | BSA A50 CYCLONE 500 ROYAL STAR 1962 - 1970 |
| Year | 1962 - 1970 |
| Engine Type | Four stroke, parallel twin cylinder |
| Displacement / Capacity | 498 cc / 30.4 cu in |
| Bore X Stroke | 65.5 x 74 mm |
| Compression Ratio | 9.0:1 |
| Cooling System | — |
| Max Power | 24.3 kW / 33 hp @ 5800 rpm |
| Max Torque | — |
| Ignition | Coil |
| Induction | Twin 1 1/16 in carburettors (Cyclone models) |
| Start System | — |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 4 speed |
| Clutch | Multi-plate |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Tubular steel, welded, double cradle with swingarm |
| Front Suspension | Telescopic forks |
| Rear Suspension | Twin coil-over shocks |
| Front Brakes | Drum, 8 in |
| Rear Brakes | Drum, 7 in |
| DIMENSION SPECS | |
| Overall Length | 2100 mm / 81 in |
| Overall Width | — |
| Overall Height | 1028 mm / 40.5 in (standard); 1117 mm / 44 in (Western) |
| Seat Height | 840 mm / 33 in |
| Wheelbase | 1391 mm / 54.8 in |
| Ground Clearance | — |
| Dry Weight | 141 kg / 311 lbs |
| Wet Weight | 177 kg / 391 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.25 x 19 in, ribbed |
| Rear Tyre | 4.00 x 18 in, K70 |
| FUEL SYSTEM | |
| Fuel Capacity | 18.2 Litres / 4.0 Imp gal |
| Fuel Consumption | — |
| Top Speed | about 145 km/h / 90 mph |
The A50 was BSA's 500 cc unit-construction twin, sold as the touring Royal Star and in sportier Cyclone forms with twin carburettors, including US scrambler and street styles. It shared its design with the larger A65 and stayed in the range until 1970.
