RE: SAITO ID ????
Ron:
Don't forget the engine could also be an FA-120. Check the threads on the gland nuts holding the intake and exhaust to the cylinder. If they are the same size, 14 mm, the engine is an FA-120. The FA-150 and FA-180 have a 16 mm thread on the intake with the exhaust still 14 mm.
Not a 120? If you have a known FA-150 or FA-180 it's easy to ID a stranger. Measure the depth of the groove between the side fins at the same point on both engines. If the depth is the same, they are the same size. If one is deeper, the deeper one is a 150 and the shallower one is an FA-180.
HTH.
Bill.