Try leaving your engine oil down1/4-1/2 qt next time you change oil. Or if you have to add oil, leave the level down a bit. Too often this problem is caused by overfilling, even though you are within specs. Hope this helps. Oil will always spit out of the breather. Its just the nature of the beast.
The most common cause is a grounded stator. Lack of primary oil or a too-tight chain can also cause excessive chaincase heat.
Chain too tight
A bad, stuck or dirty float needle inside the carburetor.
bad seal in between your intke manifold and carburetor
your float is stuck in the carburetor. Clean it with carb cleaner.
Usually a stuck float mechanism.
A misfire will cause flames to come out of the carburettor
carburetor or spark plugs
The float valve in the carburetor is not working properly. You will need to remove the carburetor and clean it or replace it.
needle & seat maybe dirty , also check float level
Sounds like you need to clean your carburetor. Before messing with the carburetor, check the fuel filter - it might be clogged.
More than likely, the fuel bowl float is stuck in the open position.