| Yamaha AT1 | |
| Manufacturer: | Yamaha Motor Company |
| Parent Company: | Yamaha |
| Production: | 1969 - 1971 |
| Predecessor: | n/a |
| Successor: | AT2, AT3 |
| Class: | Enduro |
| Engine: | 123cc, 2-stroke petrol |
| Top Speed: | 60mph plus |
| Power: | 11.5 BHP/7,500 r.p.m |
| Torque: | 8.5 ft-lb/6000 r.p.m |
| Transmission: | Wet, multiple disc |
| Suspension: | Front: Telescopic fork, Rear: Swinging arm |
| Brakes: | Internal expansion |
| Tyres: | Front: 3.00-18-4PR, Rear:3.25-18-4PR |
| Wheelbase: | 50.6inches |
| Length: | 77.2inches |
| Width: | 35.8inches |
| Height: | 42.9inches |
| Dry Weight: | 218lbs |
| Wet Weight: | 234lbs |
| Fuel Capacity: | 1.9gal |
| Oil Capacity: | 1.3 qts |
| Fuel Consumption: | 141.1mpgus at 25 mph |
| Turning Radius: | 75.1inches |
| Climbing Ability: | 30 degrees |
The Yamaha AT1 is a single cylinder enduro/adventure bike produced by Yamaha motor company from 1969 to 1971.
The Yamaha AT1 was available in three different models, each corresponding to the year of production. 1969 Yamaha AT1, 1970 Yamaha AT1B, 1971 Yamaha AT1C. Each year the AT1 was also available in the Motocross edition designated by an M. The M models were very similar to the regular models other than a few performance enhancing features, such as weight reduction, higher compression ratio, tuned exhaust, larger carburettor with 26 mm throttle bore, tuned gearing ratio, etc.
| Bore & Stroke | 56 x 50mm |
| Compression ratio | 7.1:1 |
| Lubrication System | Yamaha Autolube |
| Starting system | Electric for Enduro Versions and kick starter |
| Carburettor | VM24SH |
| Battery | 12V 7AH |
| Ignition system | Battery ignition |
| AT1 1969 Pearl White | AT1-100101 to AT1-119829 |
| AT1M 1969 MX Version Pearl White | AT1-300101 to AT1-303790 |
| AT1B 1970 Competition Yellow | AT1-120101 to AT1-138890 |
| AT1M-B 1970 MX Version Competition Yellow | AT1-310101 to AT1-312326 |
| AT1C 1971 Brilliant Red | AT1-139101 to AT1-162879 |
| AT1M-C 1971 MX Version Brilliant Red | AT1-313101 to AT1-317191 |