I switched from a saito 120 to the rcgf 20cc rear carb on my rascal 110. I didnt notice any real difference in vibration. Later I went back to the saito 120 on my rascal. The little bit of extra weight put the rascal over the limit by just enough that I couldnt thermal very well anymore. Nothing wrong with the engine. Just a flying style difference. I'm putting the 20cc on bandito grande I built from the Doc Mathews plans at rcm.
Edwin