So can I run carb/fuel system cleaner in an MC or is there something about MC carbs that's different enough from a car's to preclude its use?
BTW: sonce MC fuel systems are gravity fed, you will see a fine dark sediment (dirt) accumulate everywhere... the bottom of the tank, the fuel filters, the float bowls, etc....
The only way to get it clean is to take the tank off and drain it and flush it with clean solvent. Also, remove the gas feed tap assy and clean it out (you won't believe what you are going to find in there.... dirt, cat hair, rust, and other junk). The float bowls are usually easy to remove if the bike has carbs. If it's FI, they are harder to clean.
BTW: many new bikes don't come with "in'line" fuel filters and they are a REALLY GOOD idea to minimze the amount of garbage getting from the tank down into the fuel system.