Yes a bit embarrassing now I think about it. I have a cline regulator that I plan on installing because the tank is pretty far back and the engine is inverted with the tank a bit higher than the carb. Anyway, I thought I would run in the engine first without the regulator as it affects the needle settings etc and I didn't want to add any issues with running it in. SO I plumbed the tank with the regulator in mind, having a T-line for filling into the carburator line. Later, I will add a t line to the vent as well. When I filled the tank I first noticed that the carb was completely full of fuel up to the top of the velocity stack. I swore a bit for forgetting something like pinching off the carb line turned back around and the fuel was gone. I thought maybe it went down into the carburator. Checked for hydrolock, no lock, so choked it more to make sure fuel was flowing it was and seemed good. One more hydrolock check and good to go. I used a chicken stick and it started really rough, but smoothed out must have been the backfire igniting my carb.