I never got around to it on my old TXT200, but it is a worthy idea. I'd personally try a PWK28 Keihin, you can buy them for KX80s pretty cheaply off ebay and they are a better carb than any mikuni I've played with. That said if there is a well trodden path it might be the path of least resistance. Actually I did put a mikuni on my Beta aircooled which worked out ok.