JASON - K161 was a seven HP, and was the engine that should be in a '61 to '63 Cub Cadet. Even back in the early 60's most Cub Cadets were elec. start. Sounds like You need to contact one of the sponsors and get a clutch/brake pedal return spring.
Also there were actually two versions of K161's, some of the early spec numbers had 2-7/8" bore and the later versions had 2-15/16" bore. All had 2-1/2" stroke. When the K181 (8 hp) was produced it only had the 2-15/16" bore and 2-3/4" stoke.
We never talk about them here because IH/Cub Cadet never used them but Kohler also made a 4 HP K91 and a 6-1/4 hp K141 that other lawn & garden companies (Wheel Horse comes to mind) used in lawn & garden tractors.
Also there were actually two versions of K161's, some of the early spec numbers had 2-7/8" bore and the later versions had 2-15/16" bore. All had 2-1/2" stroke. When the K181 (8 hp) was produced it only had the 2-15/16" bore and 2-3/4" stoke.
We never talk about them here because IH/Cub Cadet never used them but Kohler also made a 4 HP K91 and a 6-1/4 hp K141 that other lawn & garden companies (Wheel Horse comes to mind) used in lawn & garden tractors.