| MODEL | YAMAHA DT 400 1978 - 1979 |
| Year | 1978 - 1979 |
| Engine Type | Two stroke, single cylinder, reed valve |
| Displacement / Capacity | 397 cc / 24.2 cu in |
| Bore X Stroke | 85 x 70 mm |
| Compression Ratio | 6.4:1 |
| Cooling System | Air cooled |
| Max Power | 17.1 kW / 23 hp @ 5500 rpm |
| Max Torque | 3.8 kgf-m / 27.5 lb-ft @ 5000 rpm |
| Ignition | CDI |
| Induction | Single 28 mm Mikuni carburetor |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 5 Speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | Telescopic forks |
| Rear Suspension | Swinging arm fork |
| Front Brakes | Drum |
| Rear Brakes | Drum |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | 1410 mm / 55.5 in |
| Ground Clearance | — |
| Dry Weight | 124 kg / 272 lbs |
| Wet Weight | 141 kg / 310.9 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.00-21 |
| Rear Tyre | 4.00-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 9 Litres / 2.3 US gal |
| Fuel Consumption | — |
| Top Speed | 87 mph |
The DT 400 was Yamaha's large air-cooled two-stroke single for trail and enduro riding, with reed-valve induction, CDI ignition and a five-speed gearbox. It carried over the long-travel dirt-bike layout of the DT 360 with a larger 397 cc engine and was a popular all-round dual-purpose machine of the mid to late 1970s.
