Was more or less gifted this big JD rider. Started, ran rough, blew smoke, but drove it in the trailer. Got home, zero compression on one side. Air cooled Kohler twin with a history of break downs. Totally disassemble things, to remove the engine. In the oil sump was no. 1 con rod. In 5 pieces. Online I find this engine has problems, rods breaking, oiling in general. Looked up parts. Priced things, rod, piston, rings, gaskets. Rod is aluminum, so didnt hurt the cast iron block. But decided not to throw money into a 40 years old problem engine. Ordered a HF Predator V twin 670cc. Measrements tell me it may be a good fit. Lots cheaper than the Honda some folks are using. Got the time right now, see how it goes. Anybody do engine swaps on garden tractors?