Glad to see your having fun on the mower I also have had a few opposed twins as well had some smooth running ones I have had some knocking opposed engines I had one the sump gaskets on them and sealed them up top to bottom as you keep them oil tight and the Vavles clearance when they need it other then that I think they are very good engines and glad to see your keeping yours running.
@HBY.2 pulley swaps, stock front is a 3.5 inch and stock back is a 9 inch, I swapped to a 6 on the front and a 2 on the back. Also, a gas pedal hooked directly to the carb for more rpm. Spins the input shaft of the transmission way faster, creating more speed. Only works on geared transmissions, a hydro or FNR single speed won't work.
big red did 50, but should go faster with a new engine, the custom cruiser did 31, but needs a bigger engine pulley. probably only going 25-30 mph while behind the bus
