Chris, the Kirby-built Lauson engines were mechanically durable, their main disadvantages were that they tended to be a bit temperamental when it came to cold-starting, and they had a chaffcutter-like character when they ran. They were not anywhere near as rough as a 2 stroke, but there seems to be a rather clear ordering when it comes to pleasability of the popular engines over the years. The Lauson was worst, the Briggs in the middle, and the sweetest runner (and starter) was the OHV Honda. All three are capable of lasting a long time, but if you have a Lauson, it seems even longer than it is.
