One nasty thought I had:
These Kirby-Lauson engines were running in the 50s and 60s when fuel was leaded.
What happens/happened to them with unleaded fuel? Were the valve/valve seats hardened (I'm guessing unlikely if the machine was built in Oz), and/or could this be a cause of them failing?
Well, being an aluminium alloy block, they are fitted with inserted valve seats [i.e. steel or a hard alloy]. So I'd say they will be fine with unleaded fuel, with the low compression ratios these engines run. Just take particular care to avoid any E10 fuel, for the sake of the fuel system!
Also Grumpy said in the past that:
It was not a nice engine to operate in my experience, but they were quite durable mechanically.
Does anyone have an idea about what grumpy meant by "not a nice engine to operate"?
I suspect he thought of them as a bit agricultural and unrefined - a bit prone to hard starting, excessive vibration, and not the easiest to repair [these days, at any rate].
This quote from one of his past posts is revealing:
My experience with Briggs engines is similar to yours: reliable, smooth running, easy to start, and generally easy to service and repair. Whether fortunately or un-, I took and interest in OHV Hondas a couple of years ago, which led me to dispose of my Briggs mowers and get a couple of Hondas. To me, they are as big an improvement over a side valve Briggs as the Briggs is over a Kirby-Lauson.
And with half a million made, they've gotta be scattered around all over the place even now? Surely???
They aren't uncommon, for sure. But not that many of them are still in running condition. I can't recall exactly when Kirby ceased making engines, but it would have been around the late 1970's.
Scott Bonnar had certainly dropped them from all models by 1978. Victa had done so by 1973, and gone to Briggs on their sole 4-stroke offering.
