Now that's a trick tool i'd not thought of making. I'd be worried about putting holding pressure on the spring posts if he nut was too tight, but i guess spread over 5 posts it sounds like it must be strong enough.
I'll check out my AT1 carb tomorrow if i remember as possibly one blocked off for a reason as they do. But would be blocked off with a solid plug normally.

Just thought I’d try with a photo this time. Soaked in berryman dip for about an hour then ran a small drill bit (only slowly and by light finger spinning with no pressure) down the right bottom hole on the air inlet Carb opening. A bunch more gunk came out but it’s still not blowing through that I can tell. The bike starts fairly easily and seems to rev fine at higher RPMs but it won’t idle and you have to feather the throttle until it smooths out at higher RPMs. All other passages seem clear so I suspect this passage is the culprit. Anyone know the function of this channel?