Welcome to the 1975 Yamaha DT400B Forum. Feel free to post anything related to this model in the category. The factory color was called Competition Yellow. The USA Vin range was 501-000101 to 025076. Anything new, will be added to this section. If you see any errors, please contact me privately.

                    1975 Yamaha DT400B Specifications

            Model 1975 Yamaha 400B

   Dimensions:

Overall Length -

Overall Width -

Overall Height -

Wheelbase -

Min. Ground Clearance -

    Weight:

Gross -

Net 272 Lbs.

   Performance:

Max, Speed -

Fuel Consumption -

(On paved level roads)

Climbing Ability -

Min. Turning Radius -

Braking Distance -

   Engine: Induction System

Model DT400B

Type 2 Stroke, Gasoline

Lubricating System Separate (Yamaha Autolube)

Cylinder Single, Reed Valve, 7 Port, Air Cooled

Displacement 24.22 cu. in. (397cc)

Bore X Stroke 85MM X 70MM

Compression Ratio 6.4:1

Max Power -

Max Torque -                         

Piston Skirt Clearance new .0015 - .0018 In./ 0.40 - 0.45MM  

Max .01MM (.004")                                       

Starting System Primary-Coupled Kick

Ignition Timing B.T.D.C 2.9MM +/- .015MM

NGK Spark Plug & Gap B-9ES 0.5 - 0.6 MM

Contact Break Point Gap -

Ring End Gap Top/2nd 0.3 - 0.5MM (.012 - .20") / Same

Ring Groove Clearance Top/2nd 0.3 - 0.8MM (.012 - .0032") / Same

Condenser Capacity -

   Carburetor:

Type 50061 VM32SS

Main Jet # 160

Jet Needle 6F9-4

Air Jet 2.5MM

Needle Jet 0 - 8

Cut Away 3.0

Pilot Jet (#) 40

Air Screw (turns out) 1 1/2

Starter Jet (#) 60

Float Level 23MM +/- 1.0MM

  Intake:

Air Cleaner Wet, Foam Rubber

   Transmission:

Clutch Wet, Multiple Disk

Primary reduction system Helical Gear

Primary reduction ratio 2.666 / (64/24) Teeth

Trans Oil Capacity 1000cc (33.8oz.)

   Gear Box:

Type Constant Mesh, 5 Speed Forward

1st Gear teeth, Ratio, O.A. 2.533 (38/15) 19.302

2nd Gear teeth, Ratio, O.A. 1.789 (34/19) 13.634

3rd Gear teeth, Ratio, O.A. 1.304 (30/23) 9.938

4th Gear teeth Ratio, O.A. 1.000 (26/26) 7.619

5th Gear teeth Ratio, O.A. 0.766 (23/30) 5.841

Secondary reduction system Chain DID520DS 97 Links

Secondary reduction ratio 2.857 (40/14)

  Chassis:

Frame Tubular-Double Loop

Front Suspension System Front Telescopic fork

Rear Suspension System Swinging Arm

Rear Shock Oil Capacity 181cc (6.1 Oz.)

Fork Oil Capacity 175cc (5.9 Oz.)

Front Cushion System Coil Spring / Oil Damper

Rear Cushion System Coil Spring / Oil Damper

  Steering System:

Steering Angle 49 Degrees both left & right

Caster 60.5 Degrees

Trail 4.72 In. / 120MM

  Braking System:

Type of brake Internal Expansion

Front Operation System Right hand operation

Rear Operation System Right foot operation

  Tire Size:

Front 3.00 - 21 - 4PR Trials Universal

Rear 4.00 - 18 - 4PR Trials Universal

Front Tire Pressure 13 P.S.I (Add 10P.S.I For Street)

Rear Tire Pressure 16 P.S.I (Add 10P.S.I For Street)

  Oil Pump:

Adjustment Stroke Min 0.20 - 0.25 MM

Adjustment Stroke Max 1.85 - 2.05 MM

  CDI Magneto Outer Rotor:

Model FOT02173

Manufacturer Mitsubishi

  Battery:

Model 6N4B-2A-3

Manufacturer G.S or F.B.

Rating 6V 4AH

 Electrical:

Head Light 6V 25W/25W

Tail Light 6V 5.3W/17W

No Load Voltage Ad. (AC & DC generators) Yellow: 0.23 Omhs

Green 1.73 Omhs / Red 0.54 Omhs

Max Generator (Magneto) Output 8.5V 3.2A @8,000 RPM

 Ignition Coil Min. Spark Gap/Pri. Res./Sec. Res 6MM/1.02Omhs/6.0KOmhs

Tanks:

Gasoline Tank Capacity 2.4 Gallons

Oil Tank Capacity 1.6 Quarts

  Chain:

Tension (Up & down free play) 20MM (25/32)

The 1975 Yamaha Owner's Warranty Guide Book Is Located: CLICK HERE

The 1975 Yamaha Owner's Documentation Bag is Located: CLICK HERE

The 1975 Yamaha DT400B Owner's Manual is Located: CLICK HERE

The 1975 Yamaha DT400B Combined Serviced Manual is Located: CLICK HERE

The 1975 Yamaha DT400B Assembly Manual is Located: CLICK HERE

The 1975 Yamaha DT400B Parts Manual is Located: CLICK HERE

The euro 1975 Yamaha DT400B Service Manual supplement is located: CLICK HERE

The 1975 Yamaha Accessories Catalog is Located: CLICK HERE

The 1975 Yamaha DT400B Service Data Technical Bulletin is Located: CLICK HERE

The 1975 Yamaha Dealership Inspection Sheet is Located: CLICK HERE

The 1975 Yamaha DT400B Article # 1 is Located: CLICK HERE

The 1975 Yamaha DT400B Article # 2 is Located: CLICK HERE

The 1975 Yamaha DT400B Cycle Article # 3 is Located: CLICK HERE

The 1975 Yamaha DT400B Article # 4 is Located: CLICK HERE

The 1975 Yamaha DT400B Cycle World Article # 5 is Located: CLICK HERE

The 1975 Yamaha DT400B Advertisement # 1 is Located: CLICK HERE

The 1975 Yamaha DT400B Advertisement # 2 is Located: CLICK HERE

The 1975 Yamaha DT400B Brochure is Located: CLICK HERE

The 1975 Yamaha Enduro Brochure is Located: CLICK HERE

The 1975 Yamaha Range Brochure is Located: CLICK HERE

The Australia 1975 Yamaha DT400B Brochure is Located: CLICK HERE

The Germany 1975 Yamaha Line Up Brochure is Located: CLICK HERE

The 1975 Yamaha DT400B (with 76C Gas Tank) hobby lobby sign is Located: CLICK HERE

The 1975 Yamaha DT400B Store is Located above.