Re: DT75 - hole in top of piston
A burn hole in the top of the piston is usually caused by a lack of adequate fuel,probably caused by a defective fuel pump. The most common problem is a tiny pin hole in the the diaghram or a bent check valve inside the fuel pump. Such a small hole will permit gas to enter the crankcase and wet foul the spark plug at idle-speed. During high-speed operation, gas quantity is limited, the plug is not foul and will therefore fire in a satisfactory manner. If the fuel pump fails to perform properly, an insufficient fuel supply will be delivered to the carburetor. This lack of fuel will casue the engine to run lean, lose rpm or cause piston scoring
