I have 2 dual intakes for the 61X engine. One is a Riva, the other is an R&D.

The Riva looks honed out and looks to fit 44mm carbs. The R&D looks like a raw finish inside and looks to be for 48mm carbs.

I tried to measure the bores, but they are not round on either.

Any idea what I have? Is the Riva a bored out dual 38mm intake? Did the dual 44mm intakes maybe come this way?

Is the R&D a dual 48mm intake?

Like I said, I can't tell by measuring them, they are not close to round in shape.