| MODEL | AJS 350 BIG PORT 1923 |
| Year | 1923 |
| Engine Type | Single-cylinder four-stroke, overhead valve (pushrod and rocker) |
| Displacement / Capacity | 348.3 cc |
| Bore X Stroke | 74 mm x 81 mm |
| Compression Ratio | — |
| Cooling System | Air |
| Max Power | About 20 hp |
| Max Torque | — |
| Ignition | — |
| Induction | — |
| Start System | — |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 3-speed, separate |
| Clutch | — |
| Final Drive | — |
| CHASSIS SPECS | |
| Frame | Single tubular cradle, open below |
| Front Suspension | Elastic (springs) |
| Rear Suspension | — |
| Front Brakes | Side drum |
| Rear Brakes | Side drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | — |
| Rear Tyre | — |
| FUEL SYSTEM | |
| Fuel Capacity | — |
| Fuel Consumption | — |
| Top Speed | About 137 km/h / 85 mph |
The Big Port was the 350 cc racing single AJS took to the Isle of Man in the early 1920s, named for its unusually large exhaust ports. It won the Junior TT in 1921, 1922 and 1923 and also took the Senior in 1921, then enjoyed many Continental successes, notably in Italy.
