Bob, you’re still lowest on the S#. There were more numbers past the 21. As to your Cub. People think that the reason for the loss of compression is the ring seal to the cylinder. That is part of it. But not only where the ring contacts the cylinder but in the grooves of the piston. As the piston goes up and down, so does the ring. The clearance gets larger and if the groove is no longer parallel to the ring, the ring can rock. When a fresh motor warms up the ring end gap is only a few thousands. As the ring wears the end gap gets larger. This is the major loss of compression. If just the ring is worn, all you would have to do is replace it. However the cylinder is worn as well. If you take one old, or new ring, and check the ring end gap at the bottom of your cylinder, then push the ring close to the top, but not past where it runs, the difference in the end gap will give you a good idea of how much taper you have in your cylinder. I suspect your end gap will likely grow by .030 or more. While that will have an affect on the compression in a 2″ or 3″ cyl. bore, its huge in the 1-1/8″ bore of your Cub. My best guess as to why your motor wont run when put in water. I’m no where as confident in my abilities to use those brazing rods as you are. Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.
