if you do have suction, and assuming the cam shaft is moving, remove the main jet cap/drain at the bottom of the carburetor and see if fuel flows out. If it does, then fuel is getting to the main jet. If it is getting there, check the fuel level in the bowl. Doing this requires a special tube tool that connects to the main jet cap drain orifice, bends up the side of the bowl so you can see the fuel level. Its similar to those glass tubes on the outside of commercial coffee pots that indicate coffee level. It should be 5/8ths inch below the gasket surface. If the float is set too low, fuel will not flow out the main jet without extraordinary vacuum. Without the tool, you can roughly estimate if the float is right by checking to see if it rests with the seam parallel to the gasket surface when you invert the top. Its common for today's float valve gaskets to be so thick that the float rests too low. The float is adjusted by using vary-ing thickness of gaskets to get the float parallel. It is fine tuned using the visible tube tool.