| MODEL | YAMAHA DT 250 1978 |
| Year | 1978 |
| Engine Type | Two stroke, single cylinder |
| Displacement / Capacity | 246 cc / 15.0 cu in |
| Bore X Stroke | 70 x 64 mm |
| Compression Ratio | 6.8:1 |
| Cooling System | Air cooled |
| Max Power | 12.6 kW / 17 hp @ 6000 rpm |
| Max Torque | 20.7 Nm / 15.3 lb-ft @ 5500 rpm |
| Ignition | External-rotor magneto; CDI; six-volt battery |
| Induction | Single 28 mm Mikuni VM28SS |
| Start System | Kick |
| TRANSMISSION SPECS | |
| Lubrication | Autolube |
| Gear Box | 5 Speed |
| Clutch | — |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Double-downtube, full-cradle, mild-steel frame; tubular-section, mild-steel swing arm |
| Front Suspension | Oil-damped coil-spring fork with forward-mounted axle; 195 mm / 7.6 in travel |
| Rear Suspension | Nitrogen-charged mono-shock; 152 mm / 5.9 in travel |
| Front Brakes | Conical hub drum brake |
| Rear Brakes | Conical hub rod-actuated drum brake |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | 870 mm / 34.2 in |
| Overall Height | — |
| Seat Height | 856 mm / 33.7 in |
| Wheelbase | 1420 mm / 55.9 in |
| Ground Clearance | 255 mm / 10.0 in |
| Dry Weight | 122 kg / 269 lbs |
| Wet Weight | 131 kg / 290 lbs |
| WHEEL SPECS | |
| Front Tyre | 3.00-21 |
| Rear Tyre | 4.00-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 8.5 Litres / 2.2 US gal |
| Fuel Consumption | — |
| Top Speed | — |
For 1978 the DT250 kept the monoshock chassis introduced the year before, with capacitor-discharge ignition replacing breaker points per the road test. It remained a street-trail bike with emissions-driven detuning, a 7000 rpm rev ceiling and a weakness at high revs.
