I did a bike for my grandson,and it has some hesitation,enough that it will die.It will idle fine and runs good but you have to nurse it to get it going. I made the exhaust(one point of my question) and the intake(another question). These were what I came up with just to get done. I was hoping that jumping up to 3/4 after the bend in the exhaust would help with flow.Carb is something that was laying around for God knows how long,and no,I don't know anything about it.Let me know what you think please.