I had posted suggested bringing the top emulsion hole down in size. But I deleted it thinking that the post had turned more to tuning the SV-1.

Any emulsion holes ABOVE the fuel level in the bowls will affect the transition from the idle circuit to the mains. Assuming that the mains are not coming in too late, then I would try putting in a .010" to .015" wire in the top emulsion holes and see how it likes it.

You could also try sizing down the next lower emulsion hole if the engine likes the top hole restricted.

I know that Thumperdart doesn't like the wire test. But it is quick, easy, and effective. And they can't go anywhere so they are a safe test.

Another thing to check is the feed hole for the transition slot. Make sure it is large enough. But I see more issues with too large of a the top emulsion hole than I do with undersized transition slot feed holes.