2 stroke/4 stroke carbs?

im looking at replacing the mikunis on my suzuki t200 which is a twin cylinder 200cc 2 stroke. at the moment they are what looks to be 20mm across the part of the carb that bolts to the engine. i dont know if this is where you measure how big the carb is like the ones on ebay though. i've been looking at the 25-30mm carbs on ebay which are meant for the 4 stroke thumpstars. would these work on my bike at all? or is there a difference between 2 and 4 stroke carbs?
any help would be greatly appreciated.
cheers
chris

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