AT1MX
Category: Motocross
Manufacturer: Yamaha
Hits: 871
| Year | 1971 |
| Engine Class | 125 |
| VIN Prefix | AT1 |
| Known VIN Range (Vehicle ID Numbers) | 313101 to 317191 |
| Tank Color(s) | Brilliant Red |
| Country of Sale | USA |
| Bore (MM) | 56 |
| Stroke (MM) | 50 |
| Displacement (CC) | 123 |
| Compression Ratio (to 1) | 8.0 |
| BHP @ RPM | 18 @ 8,500 |
| Torque (kgm) @ RPM | 1.57 @ 7,500 |
| Autolube Injection? | Yes |
| Engine Cooling | Air |
| Carburetor Model | VM26SH |
| Ignition Type | Magneto |
| Ignition Timing MM (BTDC) | 2.0 |
| Primary Drive Gearing | 3.9 |
| Final Drive Gearing (Sprockets) | 45/14 |
| Box Gearing First | 3.18 |
| Box Gearing Second | 1.88 |
| Box Gearing Third | 1.37 |
| Box Gearing Fourth | 1.09 |
| Box Gearing Fifth | 0.96 |
| Fuel Capacity (L) | 7 |
| 2 Stroke Oil Tank Capacity (L) | 1.23 |
| Gearbox Oil Capacity | 0.76 |
| Fork Oil Capacity (CC/Fork Leg) | 160 |
| Front Tire (stock) | 3.00 x 18 |
| Rear Tire (stock) | 3.25 x 18 |
| Front Brake Type | Drum |
| Rear Brake Type | Drum |
| Rear Suspension | Twin Shock |
| Front Suspension Travel (mm) | 145 |
| Rear Suspension Travel (mm) | 110 |
| Rake (degrees) | 29.5 |
| Overall Width (mm) | 909 |
| Ground Clearance (mm) | 225 |
| Wheelbase (mm) | 1,285 |
| Dry Weight (kg) | 91 |
| Spark Plug | NGK B8ES |
| Voltage | 6 Volt |
| Carburetor Type | VM26SH |
| Main Jet | 190 |
| Needle Jet | 0-2 |
| Jet Needle | 4F15-2 |
| Slide Cutaway | 1.5 |
| Pilot Jet | 30 |
| Air Screw (turns out) | 1.5 |
| Starter Jet | 40 |
| Float Level (mm) | 25.5 |