| BSA M21 | BMW R 12 |
|---|
| engine specs | |
| Type | |
|---|---|
| air-cooled, four-stroke, single cylinder, side valve | Water-cooled, 2-cylinder, four-stroke boxer engine with four valves per cylinder operated by cam followers and two overhead camshafts per cylinder |
| Displacement | |
| 591 cm3 | 1170 cm3 |
| Bore X Stroke | |
| 3.2x4.4 in OR 81 mm | 4.0x2.9 in OR 102 mm |
| Compression Ratio | |
| 5.0:1 | - |
| Horsepower | |
| 15/4200 KW(hp)/RPM | 95/6500 KW(hp)/RPM |
| Torque | |
| - | 81/6000 lb-ft/RPM OR 110/6000 Nm/RPM |
| Fuel System | |
| Amal carburetor | - |
| transmission specs | |
| Gearbox | |
|---|---|
| 4-speed, manual | 6-speed |
| Clutch | |
| dry, multi-plate | - |
| Final Drive | |
| chain | Shaft |
| chassis specs | |
| Frame | |
|---|---|
| steel | Tubular space frame in steel, engine self-supporting |
| Front Suspension | |
| single spring girder fork | USD telescopic forks, 45 mm |
| Rear Suspension | |
| hard-tail, sprung seat | Aluminium Paralever swinging arm, directly linked WAD spring strut, spring base and rebound damping adjustable |
| Front Brake | |
| drum | Twin disc brake, floating brake discs, 310 mm, 4-piston monobloc fixed calipers |
| Rear Brake | |
| drum | Single disc brake, 265 mm, 2-piston floating caliper |
| dimension specs | |
| Overall Length | |
|---|---|
| 85.8 in OR 2179 mm | 86.6 in OR 2200 mm |
| Overall Width | |
| 29.1 in OR 739 mm | 32.7 in OR 831 mm |
| Seat Height | |
| 28.5 in OR 724 mm | 29.7 in OR 754 mm |
| Ground Clearance | |
| 4.6 in OR 117 mm | - |
| Weight | |
| 368 lbs OR 167 kg | 500 lbs OR 227 kg |
| Fuel Capacity | |
| 3.7 gallons OR 14.0 L | 3.7 gallons OR 14.0 L |
| Wheelbase | |
| 54 in OR 1372 mm | 59.8 in OR 1519 mm |
| tyres specs | |
| Front | |
|---|---|
| 3.25 x 19 | 100/90-19 |
| Rear | |
| 3.50 x 19 | 150/80-16 |
