Yamaha RD400

The RD400 is a 399 cc (24.3 cu in) two-stroke air cooled six-speed motorcycle produced by Yamaha from 1976 until 1979. It evolved directly from the Yamaha RD350 The 350 evolved into the RD400C in 1976, the "D" and "E" in '77–'78 and the final model, the white 1979 RD400F. (The model year for the first RD400, which was sold in the U.S. in the summer of 1975, was 1976.)

RD400

1978 Yamaha 400 DX
Manufacturer	Yamaha Motor Company
Production	1975–1980
Predecessor	Yamaha RD350
Successor	Yamaha RD350LC Yamaha RZ350
Class	Standard
Engine	399 cc (24.3 cu in), air-cooled, two-stroke, straight twin
Bore / stroke	64 mm × 62 mm (2.5 in × 2.4 in)
Compression ratio	6.2:1
Top speed	106.8 mph (171.9 km/h)[1]
Power	44 bhp (33 kW) @ 7,000 rpm[1]
Torque	30.3 lb⋅ft (41.1 N⋅m) @ 6,500 rpm[1]
Ignition type	Kick start: points (CDI ignition from 1978)
Transmission	6-speed manual, chain final drive
Frame type	Tubular twin cradle
Suspension	Front telescopic forks; rear swingarm with twin rear shock absorbers
Brakes	Single disc brake, front and rear
Rake, trail	27.5°, 110 mm (4.3 in)
Wheelbase	1,330 mm (52.5 in)
Dimensions	W: 800 mm (31.5 in)
Seat height	800 mm (31.5 in)
Weight	165 kg (364 lb) (with 4.5 l; 1.2 US gal (1 imp gal) of fuel)[1] (wet)
Fuel capacity	16.5 l (3.6 imp gal; 4.4 US gal)
Oil capacity	1.6 litres (1.7 US qt)
Fuel consumption	30 to 42 mpg‑imp (9.4 to 6.7 L/100 km; 25 to 35 mpg‑US)[1]

The brakes were single disc front and rear. It could complete a standing quarter-mile in 14.01 seconds.[1]

The RD400C was the first motorcycle by a major manufacturer to be fitted with cast wheels.[2]

In 1979 the RD was fitted with a capacitor discharge electronic ignition (CDI) unit as well as having thinner spoked cast wheels, a new foot peg position and some minor engine modifications.