The rse reed has a 19mm OD and a 15mm ID. Most of the time you see it being used with a dellorto or a cns using a sleeve to adapt. This carb. your showing would require some sort of a neck down between the reed and carb. to be fitted to a rse reed. Having a big ol carb, then necking it down to fit a small intake and reed is IMO not the way to go to improve performance.