Got an old Monkey Wards Sea King .7.5 by Chrysler, and I am stumped.
It won't run on the bottom cylinder, not matter what I do. So far, I've :

changed the head, head gasket, coil, converted to electronic ignition,
went over the carb (twice), two new sets of plugs, looked at the reed
valves, and it STILL won't run regularly on that bottom cylinder. Runs
fine on the top cylinder, and every now and then you hear I occasionally
hear it pop and shutter, and hear it kick in, but for the most part, the
bottom cylinder won't run. Plug just black, sometime fluffy black,
sometime wet black. I even looked at the fuel pump diaphragm
under a magnifier glass, and it too looks fine. So what the heck
could I be missing here? Compression is at 150 Lbs. I just don't
get it. The only thing I can think of is the bottom crankcase seal
is bad, and I'm sucking in air or water or something. I even took
off the exhaust manifold plate to make sure the exhaust port wasn't
plugged. Peeked in the exhaust port, and the edge of the piston
looks fine. Surely someone have the missing clue, help!!

Thanks !