If there is too much gasoline in relation to the amount of oil used, this is known as a rich mixture and hence caused the chainsaw to run in an irregular manner. How to Adjust the Carburetor on an Eager Beaver Chainsaw. Use big lines will for fuel filter lines connected to the inside of the tank.Also, use smaller of two lines for return to the fuel tank from the carburetor from the primer bulb. Stalling is a symptom of a complication in the chain-saw. //-->,