For starters, REPLACE the gray fuel lines, before you puke up your motor.
I am persuaded that they are responsible for more than a few rebuilds. As in ONE carb clogged up, first but not the other. So, one ran lean, and burned out a piston.
I repeat, change the fuel lines, BEFORE you run it!
(unless somebody else already did it)
The gray ones are disintegrating, into the fuel as we speak...
Nate