Picked up a 75 honda 400 4. Been sittin for 20 years with 4000 or so miles on it. Turns over, good compression, everything is tits, but the carbs are a wreck. Pulled them this morining and the are all stuck and gummed. Floats dont move so on and so on. What should I soak them in (solvent??) that wont eat the seals i wont be replacing with the rebuild kits?