If you have the tiny O-rings that's awesome! Those idle screws adjust how much air bleeds in during idle, but if they are leaking (as I bet yours are) they will throw off the A/F mix everywhere. Those O-rings get eaten up if you dip the carbs. They are also just old and most likely just worn and cracked already. Those air screws were capped at the factory to prevent you from messing up the emissions which were carefully set and measured at the factory. lol Be extra careful when drilling the caps, then be extra, EXTRA careful to screw them in and count the turns until they bottom out. you need to know how many turns, BUT the tips are fragile and can break off if you bottom them out too hard. Just barely turn them until they hit bottom.
This would explain why it only rev's with the choke on. You have an air leak, and the choke is contributing more fuel to the mix.
So the thing to work through is making absolutely sure you have no air leaks from the airbox lid to the airbox-to-carb boots, the carbs themselves, and most importantly the carb-to-engine boots. Those get cracked over time and leak air. I replaced mine with radiator hose which worked really well, but you'r may have the kind that bolt to the engine. Mine is a hose clamp on the engine side as well. Having a completely sealed intake system is the key to a good running bike.
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