I would drive it around some and recheck #4 cylinder when hot and right after I knew it was running decent. A low compression engine doesn't create enough air flow at idle, thus starving the engine of fuel. Yours should be OK with just one a little low.
How does the exhaust smell? and how sooty is the tail pipe?
Can you change idle quality with the idle adjustment screws?
And finally, have you synchronized both carbs to each other? that includes linkage, idle speed, and idle adjustment.
Joe
