G'day Bon_Scott
That's a pretty clever user name there, paying homage to AUS music and ... mowers!

Yes, for about a season or two in the mid-1970s, SB used a black
chaincase and handle plate. My best guess here is the 1974-75 season,
with Kirby, black bits and older logo.

I think the Kirby was discontinued for the 1975-76 season and the black bits
were discontinued for the 1976-77 season. That's about right.

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/85032/brochure-c1976.html#Post85032

Quote
I'm not familiar with the Kirby engine I have read that they weren't as good as the Briggs
Folks have said that ... but it goes to personal preference.

The Kirby has a PTO side ball-bearing and a cast iron sleeve.
The Briggs spec (for the 45) did not.

The Kirby did appear to have had a finicky carburettor and governor spring system.
I suspect poor availability of Kirby parts is a contributing factor as to reputation now.

You're lucky you have an easy choice here - a change of engine requires
no substantive modification. Keep the Kirby as a back-up option for originality down the track.
I do not feel the space-time continuum will be disrupted anymore than the name Bon Scott. smile

Please keep us informed.

bon app�tit
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Jack

p.s. I now see Mod BB has replied.
I think we are generally in agreement. laugh

Last edited by CyberJack; 08/11/18 09:02 PM.