Carburettor Breather?

[Dead Eye]

That's a photo of the old carb that is currently not attached to the engine - made for an easier photo

I may remove the carbs as I know the float bowls can be a pain otherwise. I'm guessing the pipe I highlighted is an overflow?

With the overfuelling, would this affect the jets as well and cause the mixture to be too rich, stopping the engine from firing correctly? It wouldn't start, but to be honest it was a pain in the ass when it WAS running nearly 2 years ago...