| Year | 1981 |
| Bore x Stroke | 82 x 61.5 mm |
| Capacity | 649.6 cc / 39.6 cu-in |
| Compression Ratio | 9.2:1 |
| Cooling System | Air cooled |
| Engine | Four stroke, two cylinder horizontally opposed Boxer, pushrod operated 2 valves per cylinder |
| Final Drive | Shaft |
| Front Brakes | 2 x 260mm discs, 2 piston calipers |
| Front Suspension | Telescopic hydraulic forks |
| Front Tyre | 3.25 - S18 |
| Front Wheel Travel | 175 mm / 6.9 in |
| Fuel Capacity | 22 Litres / 5.8 US gal |
| Ignition | Bosch contact free electronic ignition |
| Induction | 2 x Bing constant depression carburetors |
| Max Power | 45 hp / 32.8 kw @ 7250 rpm |
| Max Torque | 45 Nm / 4.6 kgf-m / 33.2 lb-ft @ 6000 rpm |
| Rear Brakes | Single 200mm disc, 1 piston caliper |
| Rear Suspension | Long swinging arm with adjustable strut |
| Rear Tyre | 4.00 -S18 |
| Rear Wheel Travel | 110 mm / 4.3 in |
| Starting | Electric |
| Transmission | 5 Speed |
| Wet Weight | 207 kg / 465 lbs |
