The engine in the picture is a 100cc 60102 (note the small shallow fuel tank), so some time between 1963 and 1968 Briggs must have increased the advertised power of the 60102 from 2 hp to 2.25 hp. I'm a bit surprised that seemed like a good idea when the advertised power of the 127cc 80102 was 2.5 hp. Not a good look.
So, by 1968 the 60102 and 60202 were both advertised as 2.25 hp. Whenever the 61202 appeared, it was also advertised as 2.25 hp.
The 17" and 20" SB45s were introduced with Kirby Lauson engines. Some years later, the 14" acquired a Kirby Lauson instead of a Briggs (remarkable decision) and kept it for a period after the 17" and 20" changed to Briggs.
Presumably Scott Bonnar had some business reason for putting the Kirby Lauson on the 14". I could make up some possible ones, but it would be depressing to try. It must have been a better mower with the Briggs.
