Checked the compression on both cylinders and reads 180 psi (182 psi exactly on both).
Had lost coolant slowly through SOMEWHERE I can't find, and hot light had come on. Added coolant, and proceeded to continue mowing. Then, I had about a 2 second cloud of white smoke, then ran another minute or two and same cloud of white smoke, so I brought it in and shut it down. That's when I tore it down to the motor, and found only that two carb mounting nuts were loose, and tightened them. NO COOLANT leaking anywhere that I could find, and radiator was very nearly full. Thermostat is only 4 months old, and hoses are all good.
Any ideas or experience with this type of problem?
I was thinking that it appears the intake manifold casting has 2 passages, between the cylinder heads for intake, and second passage appears to be a coolant passage? Could it be an intake gasket leak, that causes a drip into the intake to cause the smoke?