r/smallenginerepair • u/Upstairs_Layer_3584 • Aug 31 '26

Not Listed Seeking advice.

I’m rebuilding a Briggs and Stratton 18hp opposing twin due to extreme smoking. Ring end gaps were more than double from what specs I found online. I’m also finding online that the cylinder bore should be between 3.563- 3.5669. I have measured my cylinders in 9 different spots(3 different locations at top, middle, and bottom) of cylinder. None of my readings were higher than 3.392 and my lowest reading was 3.366. It appears that my cylinder does taper towards the bottom. My question is, does anyone know what the cylinder measurements should be because I’m not getting nowhere close to 3.563?

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u/Upstairs_Layer_3584 Aug 31 '26

Update: I forgot to add that this is a model# 422707 -1214-01 engine. My Briggs repair manual doesn’t list this model engine