Unfortunately the pic of the SB45 does not show the captive cotter clearly, I think I can just see the nut of the cotter, underneath the inner clutch half in the 2nd and 3rd pics. I would still like to know the exact diameter of the Kirby shaft free end...but I have a feeling Barry will be right, and it will be 3/4"....I have just checked the output free end of my Honda G100 and it is 5/8" the same as the Briggs and Stratton.
So....we may need a new inner clutch-half in any case (or modify the existing one) to fit a new (or second hand) engine....Honda, Briggs, Chonda, et al.... wink
cheers2

Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member.
Kindest Regards, Darryl grin