Check all linkages and cables, while engine is on and make sure both carbs are opening up and actually squirting fuel. Check the plugs for signs of lean or rich. I wouldn't bother with a leak down/compression test. Most likely some gunk in one of the carbs. Best of luck to you. I've been down the dual carb issue road before. Twice the headache but looks great and performs bitchin when dialed in.
