| MODEL | YAMAHA XS 650F 1979 |
| Year | 1979 |
| Engine Type | Four-stroke, parallel twin, SOHC, 2 valves per cylinder |
| Displacement / Capacity | 653 cc / 39.8 cu in |
| Bore X Stroke | 75 x 74 mm |
| Compression Ratio | 8.4:1 |
| Cooling System | Air cooled |
| Max Power | 39.5 kW / 53 hp @ 7200 rpm |
| Max Torque | 54 Nm / 5.5 kgf-m / 39.8 lb-ft @ 6800 rpm |
| Ignition | Battery, induction coil |
| Induction | 2 x Mikuni BS38 carburetors |
| Start System | Electric and kick |
| TRANSMISSION SPECS | |
| Lubrication | Wet sump |
| Gear Box | 5-speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | Telescopic forks |
| Rear Suspension | Dual shock absorbers |
| Front Brakes | Twin hydraulic discs, 267 mm |
| Rear Brakes | Drum |
| DIMENSION SPECS | |
| Overall Length | 2175 mm / 85.6 in |
| Overall Width | 780 mm / 30.7 in |
| Overall Height | 1090 mm / 42.9 in |
| Seat Height | 810 mm / 31.9 in |
| Wheelbase | 1435 mm / 56.5 in |
| Ground Clearance | 150 mm / 5.5 in |
| Dry Weight | 191 kg / 420 lbs |
| Wet Weight | 217 kg / 478 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.50H-19 4PR |
| Rear Tyre | 4.00H-18 4PR |
| FUEL SYSTEM | |
| Fuel Capacity | 15 Litres / 4.0 US gal |
| Fuel Consumption | 5.0 L/100 km / 20 km/l / 47 US mpg |
| Top Speed | 185 km/h / 115 mph |
The 1979 XS650F is the standard roadster, tested by Cycle World as smooth for a vertical twin with a low centre of gravity and good economy. Criticisms were driveline snatch at low speed and a rear drum brake that locked easily.
