What carb are you looking at?
Most four stroke carbs (at least the newer units) have an acceleration pump built in - that won't work on a two banger. Instant flooding. Trying to put an FCR carb on a two stroke will be a lesson in aggravation.
The jetting will be off.
Four stroke specific carbs often have a more sensitive low end circuit or circuits. They feed the engine half the amount as a two stroke carb and they deal with a larger vacuum signal from the engine.
It can be done, though, but it's a pain in the butt.
I used to run a two stroke carb on an old XR500 - what a mess that was...