The cracked piston is why you have no compression as the cylinder goes up to compress the air/fuel mixture that mixture is going into the crankcase and the fuel will mix with the oil causing further engine problems by degrading the oil if it's a four stroke. if it is a two stroke you will pressurize the crankcase and blow out the crank seals and without the crank seals you won't get any fuel so you'll have 2 problems..to answer your question definatley replace the piston check the ring gaps check your cylinder walls for scoring and replace ALL gaskets or seals that you took off with new ones esspecially the head gasket
foxy, March 2007
