Yamaha RD400

Yamaha RD400 (1976-1978) Specifications, Pros and Cons

Yamaha RD400 Specifications

Engine2-stroke, air-cooled parallel twin
Displacement398 cc
Bore x Stroke64 mm x 62 mm
Compression Ratio6.4:1
Power44 hp @ 7,500 rpm
Torque39 Nm @ 6,500 rpm
Ignition SystemCDI (Capacitor Discharge Ignition)
Fuel System2x Mikuni VM28SS carburetors
Transmission6-speed constant mesh gearbox
Gear Ratios1st: 2.38, 2nd: 1.71, 3rd: 1.38, 4th: 1.17, 5th: 1.04, 6th: 0.96
Front SuspensionTelescopic forks with hydraulic damping
Rear SuspensionDual shocks with adjustable preload
Front BrakeSingle disc brake
Rear BrakeDrum brake
Wheelbase1,320 mm (52.0 inches)
Weight164 kg (362 lbs)
Top SpeedApprox. 105 mph (169 km/h)

Yamaha RD400 Additional Specifications

  • Oil Type: 2-stroke motorcycle oil (typically synthetic or mineral-based)
  • Oil Capacity: Approximately 2.0 liters (around 2.1 US quarts) when changing oil and filter.
  • Gear Ratios:
    • 1st: 2.38
    • 2nd: 1.71
    • 3rd: 1.38
    • 4th: 1.17
    • 5th: 1.04
    • 6th: 0.96
  • Horsepower (BHP): 44 hp @ 7,500 rpm
  • Torque: 39 Nm @ 6,500 rpm
  • Compression Ratio: 6.4:1
  • Ignition System: Capacitor Discharge Ignition (CDI)
  • Fuel System: 2x Mikuni VM28SS carburetors
  • Transmission: 6-speed constant mesh gearbox
  • Front Suspension: Telescopic forks with hydraulic damping
  • Rear Suspension: Dual shocks with adjustable preload
  • Front Brake: Single disc brake
  • Rear Brake: Drum brake
  • Wheelbase: 1,320 mm (52.0 inches)
  • Weight: 164 kg (362 lbs)
  • Top Speed: Approximately 105 mph (169 km/h)

These specifications encompass additional technical details like gear ratios, oil type and capacity, horsepower, torque, and various other aspects of the Yamaha RD400 model.


  1. Powerful Engine: The 2-stroke, air-cooled parallel-twin engine delivers impressive power output for its size.
  2. Agile Handling: Renowned for its nimble and responsive handling, making it enjoyable on winding roads.
  3. Iconic Design: Classic styling cues and a vintage appearance that appeal to motorcycle enthusiasts.
  4. Lightweight: Relatively light for its time, contributing to its maneuverability and performance.
  5. Collectibility: Holds significant value as a classic motorcycle, attracting collectors and enthusiasts.


  1. Maintenance Intensive: Being a 2-stroke engine, it requires more frequent maintenance, including oil changes and spark plug replacements.
  2. Ride Comfort: Suspension might be considered firm, leading to a slightly stiffer ride quality.
  3. Braking System: Older models might have less advanced braking systems compared to modern motorcycles.

Yamaha RD350 vs. Yamaha RD400:


  • Engine: 347cc 2-stroke parallel-twin.
  • Power: Around 39-40 horsepower.
  • Weight: Approximately 150 kg (330 lbs) – 155 kg (342 lbs), varying slightly among different versions and models.


  • Engine: 398cc 2-stroke air-cooled parallel-twin.
  • Power: About 44 horsepower.
  • Weight: Approximately 164 kg (362 lbs).


  • Engine Size: The RD400 had a larger engine capacity (398cc) compared to the RD350 (347cc), resulting in slightly more power.
  • Weight: The RD400 was slightly heavier than the RD350, likely due to the larger engine and possibly additional components.

Both models were renowned for their agile handling and 2-stroke engine characteristics. The RD400 offered a bit more power and potentially a different riding feel due to its larger engine, but the RD350 was celebrated for its nimble nature and impressive performance in its own right.

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