Yamaha DT400

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Yamaha DT400
Also called DT400MX, DT 400 MX, DT 400
Production 1975 - 1978
Class Enduro
400cc single cylinder, two-stroke
Bore / Stroke 85.0mm x 70.0mm
Compression ratio 6.4:1
Top Speed 85 mph (136 km/h)
Horsepower 20.52 HP (15.3 KW) @ 5600RPM
Torque 20.65 ft/lbs (28.0 Nm) @ 3900RPM
Ignition cdi
Spark Plug NGK B8ES '75-78
Battery YUASA 6N6-3B-1 '77-78
YUASA 6N4B-2A-3 '75-76
Transmission Gear box: 5-speed

Final Drive: chain

Clutch: Wet multi-discs
Final Drive Chain: 520 `75-76[1]
Suspension Front: Telescopic Forks
Rear: Swinging Arm Fork
Brakes Front: expanding brake
Rear: expanding brake
Front Tire 3.00-21
Rear Tire 4.00-18
Wheelbase 55.51 inches (1410 mm)
Weight 272.05 pounds (123.4 Kg) (dry), 141.0 kg (wet)
Recommended Oil Yamalube 10w-40
Fuel Capacity 2.38 Gallon (9.00 Liters)
Value $2000
Manuals Service Manual

The Yamaha DT400MX was a single cylinder, two-stroke Enduro motorcycle produced by Yamaha between 1975 and 1978. It could reach a top speed of 85 mph (136 km/h). Max torque was 20.65 ft/lbs (28.0 Nm) @ 3900 RPM. Claimed horsepower was 20.52 HP (15.3 KW) @ 5600 RPM.

The DT400B had all the components for an enduro motorcycle including raised front and rear fenders, good ground clearance, a raised side mounted exhaust system. Stripped down, the DT400B could race in the early motocross races with similar motorcycles.

Engine[edit | edit source]

The engine was a air cooled single cylinder, two-stroke. A 85.0mm bore x 70.0mm stroke result in a displacement of just 397.0 cubic centimeters. Fuel was supplied via a membrane.

Drive[edit | edit source]

The bike has a 5-speed transmission. Power was moderated via the Wet multi-discs.

Chassis[edit | edit source]

It came with a 3.00-21 front tire and a 4.00-18 rear tire. Stopping was achieved via expanding brake in the front and a expanding brake in the rear. The front suspension was a Telescopic Forks while the rear was equipped with a Swinging Arm Fork. The DT400MX was fitted with a 2.38 Gallon (9.00 Liters) fuel tank. The bike weighed just 272.05 pounds (123.4 Kg). The wheelbase was 55.51 inches (1410 mm) long.

Major competitors[edit | edit source]

1975 DT400B[edit | edit source]

1976 DT400C[edit | edit source]

  • Starting Engine#: 501-200101

1977 DT400D[edit | edit source]

  • Starting Engine#: 1M2-000101

1978 DT400E[edit | edit source]

  • Starting Engine#: 1M2-100101

1975 - 1977 Yamaha DT 400[edit | edit source]

This new big-bore 400cc enduro. Go just about anywhere, do just about anything and do it with zip! The DT1 250 had grown up, first to 360 size, and now 400, and had become an extremely seductive machine.

1978 - 1980 Yamaha DT 400[edit | edit source]

1978 - 1980 Yamaha DT 400

The latest Yamaha DT 400 has a new monoshock frame. The DT 400 has a performance capability close to that of the pure motocross machine.

In Media[edit | edit source]

References[edit | edit source]

  1. 2019 Western Power Sports Catalog. Western Power Sports. 2019.