Originally Posted by 2door
If the engine speed increases when you disengage the clutch that is a symptom of an air (vacuum) leak somewhere in the intake circuit. Most common is where the carburetor attaches to the intake manifold or where the mainfold mounts to the cylinder.
Start looking there and we can suggest some other places if those prove to be leak free.
He said he runs without a muffler = wide open manifold, baaaadddd idea.
I also added gasket maker to the carb, as well as the loctite. I recommend you do the same, it'll save you from issues later.