1971 ATC90 K0 Specifications

General Specs
ModelATC90 K0
Model NameUS90
Model CodeUS90
Product Code918
Frame VIN LocationStamped into left side of frame neck
Engine Serial LocationStamped on bottom of left crankcase cover
Frame Starting NumberUS90-100122
Engine Starting NumberUS90E-100122
Owner Manual319182
Service Manual629181
Length1570 mm (61.8 in)
Width950 mm (37.4 in)
Height880 mm (34.6 in)
Wheelbase1010 mm (39.8 in)
Dry Weight89 kg (196.2 lb)
Caster Angle21°
Trail50 mm (1.97 in)
Tire & Rim
Front Tire Size (HxW-R)22x11-3.5
Rear Tire Size (HxW-R)22x11-3.5
Engine TypeOHC single cylinder 4 stroke air cooled
Valve TrainOverhead camshaft - chain drive
Displacement89 cc (5.4 ci)
Bore50 mm (2 in)
Stroke45.6 mm (1.8 in)
Compression Ratio8.2:1
Cylinder Compression1059-1294 kPa (154-188 psi)
Horsepower6 PS (5.9 hp)
Starter TypeRecoil
Oil Capacity - Total0.95 L (1 US qt; 0.8 Imp qt)
Drive Train & Transmission
Clutch TypeAutomatic wet multiplate centrifugal
Transmission Type4 speed constant mesh dual range
Primary Reduction3.722
First Gear2.538
Second Gear1.611
Third Gear1.190
Fourth Gear0.958
Final Reduction3.267
Identification MarkU9B
TypePiston valve
Main Jet#65
Pilot Jet/Slow Jet#35
Jet Needle Clip Position3rd groove
Pilot Screw Adjustment1 Turn out
Float Level20 mm (0.8 in)
Engine Idle1300 RPM
Fuel Tank Capacity6.5 L (1.7 US gal; 1.4 Imp gal)
Fuel Tank Reserve1 L (0.3 US gal; 0.2 Imp gal)
Ignition TypePoints
Spark PlugD-8HS (NGK)
X24FS (Denso)
Spark Plug Gap Max0.6-0.7 mm (0.024-0.028 in)
Points Gap Max0.3-0.4 mm (0.012-0.016 in)
Condenser Capacity0.25 μF
Initial Ignition Timing13.0° BTDC
Full Advance Ignition Timing25.0° BTDC
Voltage6 V
Power TypeAC
Front Brake TypeN/A
Rear Brake TypeDrum
Front SuspensionRigid
Rear SuspensionRigid

Information on this page is provided in good faith that it is accurate, but in no way is the data guanteed to be accurate. If there are any mistakes, please contact me.