150TXR is the model identity. 150 is the horse power. T is for trim and tilt. X is for an extra long shaft length of 25". R is for remote controls being required.
The number "2" makes no sense.
6G4 is the prefix for certain Yamaha two stroke 150 HP models.
The X following the 6G4 prefix denotes the shaft length. X is for 25".
The numbers following the shaft length are serial numbers for that specific 6G4 model. The letter "S" makes no sense.
The complete engine ID would be something like 6G4X 078910. The 78,910 number 6G4X model produced. Serial numbers are usually six or seven digits.
