No, it's not, and if you're hand-turning the propeller to "suck in" fuel, then you're doing something stupid. Don't do that. This is why you have a starter motor.
My Tiger Moth & my Chipmunk are a little prone to hydraulic locks having an inverted engine, but I also must be "doing something stupid" to prime and start them too. Being fitted with Armstrong Starters, I really cant avoid it.