1966 AJS Model 31 650 vs 1981 BMW R 65
Full specifications comparison •
2 motorcycles
Full Specifications
Differs
Same
| General |
| Year | 1957 - 66 | - |
| Make Model | AJS Model 31 650 | - |
| Weights & Capacities |
| Dry Weight | 176 kg / 388 lbs | - |
| Fuel Capacity | 16 L / 4.2 US gal | 22.00 litres / 5.81 gallons |
| Wet Weight | - | 204.0 kg / 449.7 lbs |
| Performance |
| Top Speed | - | 175.0 km/h / 108.7 mph |
| Max Power | 31,4 kW / 43 hp @ 6000 rpm | - |
| Engine |
| Bore x Stroke (in,) | - | 3.2 x 2.4 inches |
| Stroke | - | 4 |
| Fuel Control | - | OHV |
| Bore x Stroke (mm) | - | 82.0 x 61.5 mm |
| Engine Type | - | Two cylinder boxer |
| Displacement (ci) | - | 39.60 cubic inches |
| Displacement (cc) | - | 649.00 cc |
| Displacement | 646 cc / 39.4 cu in | - |
| Engine Detail | Four stroke, pushrod parallel twin, OHV, 2 valves per cylinder, | - |
| Bore x Stroke | 72 x 79.3 mm | - |
| Compression Ratio | 7.5 : 1 | 9.2:1 |
| Cooling System | Air cooled | - |
| Fuel Induction | Carburetor | - |
| Ignition | 6 V (After 1964 12 V) Magnet (Lucas K2F) | - |
| Starter | Kick | - |
| Valve System | - | 2 |
| Drivetrain |
| Clutch | Multi Plate (dry, Burman) | - |
| Final Drive | Chain | Shaft drive (cardan) |
| Gearbox | - | 5-speed |
| Transmission / Drive | 4 Speed | - |
| Chassis |
| Frame Type | Single cradle | - |
| Suspension - Front | Hydraulic telescopic fork | - |
| Suspension - Rear | Dual chocks | - |
| Wheels & Brakes |
| Brakes - Front | Drum | Single disc |
| Brakes - Rear | Drum | Expanding brake |
| Tyres - Front | 3.25 -19 | 3.25-18 |
| Tyres - Rear | 3.50 -19 | 4.00-18 |
| Wheels | Steel, wire spokes | - |
Verdict
⚖️
Too close to call
The 1966 AJS Model 31 650 and the 1981 BMW R 65 are evenly matched across the key measurable criteria. Your decision comes down to personal preference, riding style, and which brand's dealer network best suits your location.
Key Differences
1966 AJS Model 31 650 - Advantages
- ✓Competitive all-round: The 1966 AJS Model 31 650 matches or exceeds its rival across all measured criteria.
1981 BMW R 65 - Advantages
- ✓Competitive all-round: The 1981 BMW R 65 matches or exceeds its rival across all measured criteria.
1966 AJS Model 31 650 vs 1981 BMW R 65 - FAQs
What are the engine differences between the 1966 AJS Model 31 650 and 1981 BMW R 65?
The 1966 AJS Model 31 650 uses Four stroke, pushrod parallel twin, OHV, 2 valves per cylinder,, while the 1981 BMW R 65 is powered by Two cylinder boxer.
Which should I buy, the 1966 AJS Model 31 650 or the 1981 BMW R 65?
Both are strong choices. The 1966 AJS Model 31 650 has its own strengths, while the 1981 BMW R 65 offers a compelling alternative. Visit dealers, arrange test rides, and factor in local parts and service costs - these often matter as much as the spec sheet.