AJS Model 31 650 Swift vs Mash Dirt 650 Black (2020)
Side-by-side spec comparison, pricing, and a plain-English breakdown of how the AJS Model 31 650 Swiftstacks up against the Mash Dirt 650 Black. Numbers pulled from manufacturer spec sheets — click either bike for the full review.
Spec comparison
| Spec | AJS Model 31 650 Swift | Mash Dirt 650 Black |
|---|---|---|
| Model year | 1966 | 2020 |
| Price | — | — |
| Engine | 646 cc | 647 cc |
| Horsepower | 31 hp | 40 hp |
| Torque | — | 46 Nm |
| Weight | 176 kg | 163 kg |
| Seat height | — | 31 mm |
| Fuel capacity | 4.2 L | 3.4 L |
| Fuel type | petrol | petrol |
| Front brakes | Expanding brake (drum brake) | Single disc. ABS |
| Rear brakes | Expanding brake (drum brake) | Single disc. ABS |
| Tires | — | 120/80-18 / 130/80-18 |
AJS Model 31 650 Swift vs Mash Dirt 650 Black — which should you buy?
Picking between the AJS Model 31 650 Swift and the Mash Dirt 650 Black usually comes down to the numbers you care about most. On paper, the AJS Model 31 650 Swift brings 31 hp in a 176 kg package, while the Mash Dirt 650 Black counters with 40 hp at 163 kg.
Our spec tables above highlight the winning number on each line. For the full rider-focused reviews including real-world fuel economy, service costs and available colors, click into either bike: