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Just a few more thoughts for what it’s worth.
The compression on the top cylinder at 60 psi is a problem. An even 70 psi or higher works much better for these rotary valve motors. They don’t idle well with low compression.
The entire fuel system must be disassembled and cleaned, including the intake screen at the tank, the fuel lines, the carburetor, and especially the check valve and associated screen. A stuck check valve or clogged screen won’t allow the low speed circuit to work. A partially clogged screen at the tank could result in fuel deprivation.
One of the pictures shows some serious carbon/oil build up in the exhaust. Hopefully that’s been cleaned out.
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