I took the flywheel off and performed a leakdown test with compressed air going into the right hand carb intake. Per Paul G's suggestion (thanks), I had another pressure gauge hooked up to the left hand intake.
Upon pressuring the right cylinder to 7 psi, I could see the left cylinder pressure rising at the same rate. I could also hear air hissing out of the left crank seal, which was made very obvious when I sprayed soapy water and got large bubbles at the seal. So, the left hand crank seal is bad and I can only assume the center seal is bad if both cylinders rise and fall at the same rate, meaning the pressure of the right cylinder is directly influencing the pressure of the left, correct?
Either way, t'is the season for engine rebuilding!
