While you're at it, list ALL your mods. Pipe, type of air filter, lid/no lid, snorkle if lid, any porting, reeds, timing advance.
EVERY new build should have a leakdown test. What all was done in the rebuild? If you installed reed cage did you torque it diagonally and incrementally?
Also list what your carb jets are. Main, pilot, needle clip. If you don't know, take carb apart and find out.. Might as well clean it, and set the float, may be your problem.
Again, DON'T RUN IT UNTIL YOU FIGURE OUT THE PROBLEM !!