Yeah, I had cut up an old charcoal filter to fit... but I noticed it is VERY 'dusty'... with charcoal... because it's a charcoal filter. So I removed it because I don't want charcoal dust in the engine. I also was worried it had ZERO air flow.
Trying to find an OEM filter for it locally now (or at least some open cell foam I can cut to fit that won't shed foam into the engine.) The carb was filled with foam sludge when I removed it. I tried to find a breather filter from an auto parts store to stick on it, but no one had one the right size in stock and I didn't want to pay $25 for one on Amazon when the stock filter is like $6.