Make sure that you adjust your mixture first.
If you are still using the stock Kadron linkage than the easiest way to adjust the idle properly is to remove the linkage arms from the carburetors.
Locate the idle adjustment screw located directly in front of the carburetor. Adjust the two carburetors at the same time with your fingers by backing the
adjustment screws out until the desired idle is achieved. You would want to have the least amount of idle adjustment possible. The butterflys should be closed or close to being closed of proper seting of the mixture.. If the idle adjustment screws do not tuch the carb than that is ok. Just remember to adjust your Mixture one more time now.
Verify that one carburetor is not open more than the other by looking at the gap on the throttle body arm. Visit the Help Page for more info
in this pic you can se the LowBugget.com linkage and how it conects to your carb. Each carb gets its own return spring.