Welcome to the 1970 Yamaha HT1 Forum. Feel free to post anything related to this model in the category. The Factory paint color was called Candy Orange. The USA vin range is: HT1-200101 to 214450. Anything new, will be added to this section. If you see any errors, please contact me privately.            

                     1970 Yamaha HT1 Specifications

            Model 1970 Yamaha HT1

   Dimensions:

Overall Length 73.8 In. / 1,875MM

Overall Width 35.4 In. / 900MM

Overall Height 40.7 In. / 1,035MM

Wheelbase 48 In. / 1,220MM

Min. Ground Clearance 8.9 In. / 225MM

    Weight:

Gross 198 Lbs. / 90Kg

Net 187 Lbs. / 90Kg

   Performance:

Max, Speed 55 MPH / 95Km/h

Fuel Consumption 164.5 MPG @ 25 MPH / 70Km @ 40Km/h

(On paved level roads)

Climbing Ability 25 Degree

Min. Turning Radius 68.9 In. / 1,750MM

Braking Distance 23 Ft. @ 22 MPH (7M @ 35Km/h)

   Engine:

Model HT1

Type 2 Stroke, Gasoline

Lubricating System Separate (Yamaha Autolube)

Cylinder Single, forward inclined 5 Port

Displacement 5.43 cu. in. (89cc)

Bore X Stroke 1.969 X 1.795 In. (50 X 45.6MM)

Compression Ratio 6.8:1

Max Power 8.5 BHP/7,000 RPM

Max Torque 6.51 Ft.-Lbs @ 6,500 RPM                        

Piston Skirt Clearance .0016 - .0018 In. / 0.40 - 0.45MM                                         

Starting System Primary-Coupled Kick

Ignition Timing B.T.D.C 1.8MM +/- .1MM

NGK Spark Plug & Gap B-7H 0.5-0.6 MM

Contact Break Point Gap 0.012 - 0.015 Inch / 0.30 - 0.4 MM

Fuse 10Amp X 2

Condenser Capacity .22UF (Microfarad)

   Carburetor:

Type VM20SC

Main Jet # 85

Jet Needle 4D3-3

Air Jet -

Needle Jet N - 6

Cut Away 2.0

Pilot Jet (#) 30

Air Screw (turns out) 1 3/4

Starter Jet (#) 40

Float Level 22.5MM

  Intake:

Air Cleaner Wet, Foam Rubber

   Transmission:

Clutch Wet, Multiple Disk

Primary reduction system Helical Gear

Primary reduction ratio 3.894 / (74/19) Teeth

Trans Oil Capacity 700cc / .73 Qts

   Gear Box:

Type Constant Mesh, 5 Speed Forward

1st Gear teeth & Ratio 3.182 (35/11) 43.373

2nd Gear teeth & Ratio 2.000 (30/15) 27.263

3rd Gear teeth & Ratio 1.368 (26/19) 18.653

4th Gear teeth & Ratio 1.000 (23/23) 13.631

5th Gear teeth & Ratio 0.800 (20/25) 10.905

Secondary reduction system Chain

Secondary reduction ratio 3.500 (49/14)

  Chassis:

Frame Tubular-Double Loop

Front Suspension System Front Telescopic fork

Rear Suspension System Swinging Arm

Fork Oil Capacity 132cc - 147cc (4.5 - 5.0 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 4.3 In. / 110MM

  Braking System:

Type of brake Internal Expansion

Front Operation System Right hand operation

Rear Operation System Right foot operation

  Tire Size:

Front 2.75 - 18 - 4PR Trials Universal

Rear 3.00 - 18 - 4PR Trials Universal

Front Tire Pressure 14 P.S.I

Rear Tire Pressure 17 P.S.I

  Oil Pump:

Adjustment Stroke Min 0.20 - 0.25 MM

Adjustment Stroke Max 1.85 - 2.05 MM

  Dynamo:

Model F130-07

Manufacturer Hitachi Ltd.

  Battery:

Model 6N2-2A-3

Manufacturer Furukawa Battery

Capacity 6V 2AH

 Lighting:

Head Light 6V 25W/25W

Tail Light 6V 5.3W

Stop Light 6V 17W

Meter Light 6V 3W X 2

High Beam Indicator Light 6V 1.5W

  Tanks:

Gasoline Tank Capacity 1.7 Gallons (6.5 Liters)

Oil Tank Capacity 1.3 Quarts (1.2 Liters)

  Chain:

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

The 1970 Yamaha HT1 Rider's Manual is located: CLICK HERE

The Australia 1970 Yamaha HT1A Rider's Manual is located: CLICK HERE

The 1970 Yamaha HT1 Service Manual is located: CLICK HERE

The 1970 Yamaha HT1 Parts Manual is Located: CLICK HERE

The 1970 Yamaha HT-1 Article # 1 is Located: CLICK HERE

The 1970 Yamaha HT1 Advertisement is Located: CLICK HERE

The 1970 Yamaha HT1 Brochure is Located: CLICK HERE

The 1969-1971 Yamaha Autolube Adjustment & Color Codes are Located: CLICK HERE

The 1970 Yamaha HT1 Crankshaft Data is Located: CLICK HERE

The 1970 Yamaha Full Line Up Brochure is Located: CLICK HERE

The 1970 Yamaha HT1 Line Up Brochure is Located: CLICK HERE

The 1970 Cycle Buyers Guide is Located: CLICK HERE

The 1970 Motorcycle & Trail Biking handbook is located: CLICK HERE

The 1970 Yamaha HT1 Parts Store is Located: CLICK HERE