The Yamaha AT1 is a single cylinder enduro/adventure bike produced by Yamaha motor company from 1969-1971.

Each year the AT1 was 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 carburetor with 26 mm throttle bore, tuned gearing ratio, etc.They also did not have the extra weight of the 12 volt generator/starter setup, and ran a standard 6 volt Stator like the CT models.