| General |
| Year | 1957 - 66 | - |
| Model | Model 31 650 | - |
| Colours | - | Gray |
| Make Model | AJS Model 31 650 | - |
| Warranty | - | Two-year manufacturer?s warranty and roadside assistance for one year |
| Dimensions |
| Seat Heigth -Alternate (in.) | - | 31.6 inches |
| Seat Heigth -Alternate (mm) | - | 803 mm |
| Seat Height | - | 780 mm / 30.7 in. |
| Wheelbase | - | 1,490 mm / 58.7 in. |
| Height | - | 1,113 mm / 43.8 in. |
| Length | - | 2,184 mm / 86.0 in. |
| Width | - | 800 mm / 31.5 in. |
| Weights & Capacities |
| Dry Weight | 176 kg / 388 lbs | 179.2 kg / 395.0 lbs |
| Fuel Capacity | 16 L / 4.2 US gal | 21.95 litres / 5.80 gallons |
| Performance |
| Top Speed | - | 70.0 km/h / 43.5 mph |
| Max Power | 31,4 kW / 43 hp @ 6000 rpm | - |
| Max Torque | - | 57.90 Nm (5.9 kgf-m or 42.7 ft.lbs) @ 5000 |
| Power-to-Weight Ratio | - | 0.2769 HP/kg |
| Engine |
| Bore x Stroke (mm) | - | 87.5 x 82.0 mm |
| Bore x Stroke (in,) | - | 3.4 x 3.2 inches |
| Displacement (cc) | - | 744.00 cc |
| Displacement (ci) | - | 45.40 cubic inches |
| Engine Type | - | V2, four-stroke |
| Displacement | 646 cc / 39.4 cu in | - |
| Engine Detail | Four stroke, pushrod parallel twin, OHV, 2 valves per cylinder, | 90° V-twin |
| Fuel System | - | Injection. Weber-Marelli electronic fuel injection. |
| Bore x Stroke | 72 x 79.3 mm | - |
| Compression Ratio | 7.5 : 1 | 10.2:1 |
| Cooling System | Air cooled | - |
| Engine Lubrication | - | Forced circulation with lobe pump - circuit capacity: 1.78 Kg |
| Exhaust | - | Three-way catalytic converter with double lambda probe |
| Fuel Induction | Carburetor | - |
| Fuel Reserve | - | 3.79 litres / 1.00 gallons |
| Ignition | 6 V (After 1964 12 V) Magnet (Lucas K2F) | ECU |
| Starter | Kick | Electric |
| Drivetrain |
| Clutch | Multi Plate (dry, Burman) | Dry single plate with flexible couplings |
| Final Drive | Chain | Shaft drive (cardan) |
| Gearbox | - | 5-speed |
| Primary Drive | - | CA.R.C. Compact Reactive Shaft Drive |
| Transmission / Drive | 4 Speed | - |
| Chassis |
| Frame Type | Single cradle | Double cradle tubular frame in ALS steel with detachable rear subframe |
| Suspension - Front | Hydraulic telescopic fork | Telescopic hydraulic fork with 40 mm stanchions |
| Suspension - Rear | Dual chocks | Die cast light alloy swing arm with 2 spring preload adjustable shock absorbers |
| Wheels & Brakes |
| Brakes - Front Diameter (in.) | - | 12.6 inches |
| Brakes - Front Diameter (mm) | - | 320 mm |
| Brakes - Rear Diameter (in.) | - | 10.2 inches |
| Brakes - Rear Diameter (mm) | - | 260 mm |
| Brakes - Front | Drum | Single disc. Brembo caliper with 4 differentiated pistons |
| Brakes - Rear | Drum | Single disc. Floating disc. Two-piston calipers. |
| Rims | - | Spoked polished aluminium rims |
| Tyres - Front | 3.25 -19 | 185/88-12 |
| Tyres - Rear | 3.50 -19 | 130/80-17 |
| Wheels | Steel, wire spokes | - |