Right, the mower is used to tow around a lawn vacuum....the guy is worried about "engine smoke". I wanted to price out parts with a labor cost to set him up to reconsider the rebuild cost versus what little cost in oil he pays now.And you won't about the taper/oval until the cylinder is honed out with a ridge hone. Don't even buy the parts until you do.
Well if it is the above engine here is a 0.020 over kit that take out all the figuring.
.020" PISTON & VALVES OVERHAUL KIT FITS BRIGGS 33 CUBIC INCH SINGLE