My experience with my first 4 stroke. Saito 72. Cranked ok with the high speed needle set rich. Had about 1/4 throttle and was using an electric starter.

Never would idle. Factory tells you low speed needle flush with with the throttle arm. Not mine, about 8 turns in. Started adjusting with it closed then opened until I got a nice idle.

As for leaking. I will not buy another Saito. Mine spits fuel out everywhere. I think the cooling fins leak.

As others have mentioned. Get someone to help you with the initial set-up and starting. I also wonder if you have the wrong size fuel lines. Should not be loose, clamps are a great idea but they are not; or should not; be a must. Line should be a tight fit over the nipples. I bought the wrong size once, it fit, but not tightly. Clamps to make sure they stay in place and a little insurance against drawing air into the fuel line. A killer. I always use a clear line between the needle and the carb so I can see bubbles or fuel easily. Easy for my eyes