Yanmar Engine - Y Series
These horizontal models lay down in a low profile. The series was updated three times with the YSE being the earliest model, followed by the YSB and then the YSM. Either a 2:1 or 3:1 transmission. The models were sea-water cooled, singe cylinder, heavy duty. This series includes the following engines:
| Engine | HP | Years In Production | Comments |
| YSB12 | 12 | 1976 - 1977 | B=Between |
| YSB8 | 8 | 1976 - 1977 | B=Between |
| YSE12 | 12 | 1974 - 1976 | E=Early |
| YSE8 | 8 | 1974 - 1976 | E=Early |
| YSM12 | 12 | 1977 - 1980 | M=Modern |
| YSM8 | 8 | 1977 - 1980 | M=Modern |