gcb

Dave,

Since it ran fine before you reversed the cylinder, I would guess that the problem is a leak between the backplate and the crankcase.

Check that the rear of the crankcase is flat. Some have not been.

Next, check that there is no grit, cuts, dents, etc. on the existing gasket. You should not need gasket sealer unless the gasket is damaged and you don't want to make/locate another.

Also, when tightening screws, just snug them up until all are in place, then tighten. Preferably tighten one, then the one across from it.

Good luck with it.

George