Get rid of old Fuel residue ...

I just bought a 2 cycle130 hp ,
2000 Yamaha V4.
The owner swears that he only ran non ethanol in it
It appears that the carbs need rebuilding
My question, what's the best way to get old crusty fuel deposits out of a carb ? I have used Snow Bowl to successfully remove aluminum electrolysis, but haven't found a for sure solution to dissolve petroleum products ???