Bike will run, but won't idle

I assume that you already have tried adjusting the idle speed screw.
First guess in an air leak between the carb and manifold or manifold to cylinder.
This would affect the air to fuel ratio greatly and explain why the engine does not have enough power to climb slight inclines.
Second guess is the carburetor's slide is installed backwards.
Third guess is the throttle cable is adjusted too tight or binding inside the cable housing.

How much pre-mix oil are you adding to the gasoline to create the fuel?

Assuming that you are using regular petroleum pre-mix and not synthetic, 24:1 would be better for break in. Switch to 32:1 after the first 4 tank fulls or 2 gallons, whichever comes later.

Don't forget to check every single fastener on the whole bike for proper tightness, especially the cylinder head bolts for proper torque as the engine breaks in.
This does not mean tighten them every check. If they are loose then tighten them to 120 to 140 INCH pounds for 8mm studs/ 60 to 80 INCH pounds for 6mm studs. (An inch pound torque wrench is a very good tool to own.)
Determining which cylinder studs your engine has is critical here. For a size reference, the engine mount studs are 6mm.
This will help prevent blown cylinder head and base gaskets, engine mounts that mysteriously dissapear and a bicycle that rattles apart.

Over time everything will settle in and only a few nuts and bolts will require tending to regularly. The machine will let you know which ones they are.

I am glad to hear that you got it all worked out!

Yeaaaaaaa! Hawwwwwww!

Ride safe and enjoy.....

Great job GearNut